In Wanheda (Part 1), at Arkadia, Bellamy and Lincoln are sparring while a group of people, including Monroe and Harper, watch. Lincoln wins the fight and tells them that Bellamy was too aggressive and that is why he lost. When Lincoln gets his uniform,Bellamy tells everyone that they can make the uniform mean something different down here than it meant up on the Ark. Bellamy goes to leave for a mapping mission of Sector 7, which Lincoln says puts them on the Ice Nation border and asks to go along. Bellamy tells him he can't because of the Commander's kill order on his head.
Bellamy goes to see Kane about going into Sector 7. Kane grants permission to go into Sector 7 with weapons but re-enforces the "non-lethal response" rule since there hasn't been any Grounder attacks since Mount Weather. Bellamy leaves and searches out Monty for the mapping run. Jasper is passed out drunk under a table and Bellamy wants to leave him but Monty convinces him to bring Jasper because Jasper needs it after Maya's death. Bellamy leaves Jasper with Monty and goes over to see Gina, his girlfriend who just came back from a supply run from Mount Weather. They kiss and Gina gives him a book she brought back, The Iliad since she knew his mom used to read it to him. Bellamy walks over to the rover they will be using on their mapping mission and Raven slides out from underneath it. Miller shows up and Bellamy tosses him a gun. Jasper grabs Monty and shoves him against the side of the rover after he woke him up. Bellamy jumps in and tells Jasper he doesn't get a gun until he is sober. Jasper says he doesn't want one and disrespectfully slaps Bellamy upside the head before getting into the vehicle. Bellamy kisses Gina goodbye and climbs in with everyone else, with Raven driving. They leave through the gates of Arkadia and head out on their mapping mission.
While driving along Jasper starts singing along with the song (Add It Up by the Violent Femmes) and soon Raven and Miller join in. Their sing-a-long is interrupted by the sound of a tracking beacon from Farm Station going off after four months. They stop and Octavia rides up on her horse, asking why they stopped. Since Monty and Miller's boyfriend are both from Farm Station, Bellamy says Monty and Miller get to decide whether or not they go into Ice Nation territory and they both agree.
In Sector 7, they reach the border to Sector 8 and Ice Nation territory. Bellamy reminds them to use non-lethal force as the beacon signal draws nearer to them. Three Ice Nation warriors break through the tree line on horses, identified by their white war paint. Octavia tells them they are Skaikru looking for their people. The Ice Nation warrior asks if they're looking for Wanheda. The warrior takes Jasper hostage and starts to slit his throat. Bellamy shoots him in the arm while Raven and Miller kill the other two warriors. The wounded warrior rises up to kill Jasper and Octavia throws her sword at him, killing him.
Kane comes in over the radio, asking for Bellamy to come to Sector 4. Monty and Bellamy take the rover and head to Sector 4. Once Bellamy and Monty arrive at Sector 4, they walk to meet Kane. Monty tells Bellamy that Jasper is damaged and getting worse. They encounter Kane and Indra. Indra has come to warn them that Clarke is being hunted by everyone. Indra and Kane are riding in the back of the rover with Monty driving and Bellamy in the front seat. Bellamy comments on the kill order on Clarke. Indra clarifies that it is a bounty and that Clarke is a symbol known as Wanheda, the Commander of Death. They drive into Sector 7 and Indra tells them to start at the trading posts in order to find Clarke. Monty is still driving Bellamy, Kane, and Indra in the rover to Sector 7. Monty slams on the breaks when the rover's path is blocked by a felled tree. Indra tells them it was cut down but Bellamy doesn't believe her until another tree falls behind their rover, effectively trapping them.
In Wanheda (Part 2), Bellamy, Monty, Indra, and Kane have been trapped in Sector 7 in the rover for three hours waiting for something to happen. Bellamy pokes his head out the moon roof and suddenly has a knife to his throat. The rest of them are ordered out of the rover as Bellamy is yanked out through the moon-roof. Monty tries to fight them and Bellamy calls out his name to get him to stop. One of the warriors repeats Monty's name and Monty recognizes her voice as his mother's. Pike orders the rest of them to stand down and greets Kane and Bellamy. He calls them "Grounder killers" and everyone cheers. Bellamy interrupts and tells them they need to find Clarke. They go to move the trees blocking the rover and Bellamy asks Monty if he is okay. They get the trees out of the way of the rover and Kane sends the Farm Station warriors to collect the rest of their people and head to Arkadia.
At the trading post, Roan's bounty hunter partner is about to cut off Niylah's hand when Bellamy shoots him dead. Bellamy pleads with Niylah to tell them about Clarke. Niylah recognizes him as Skaikru and tells him that Clarke was there last night and the bounty hunter told her his partner was Ice Nation. Bellamy thanks her as Monty comes back to tell them he found their tracks but they can't take the rover because there are too many trees.
Pike and Bellamy are walking through the same field where Roan and Clarke previously were. Pike asks Bellamy why they seem to be getting along with the Grounders and Bellamy tells him it was because they had a common enemy and they won. Bellamy spots Roan and Clarke far on the other side of the field as Kane spots the incoming army advancing from another end of the field, separating them from Clarke. Bellamy wants to go after Clarke but they are stuck in the cave with the corpses of the three Ice Nation scouts as they wait for the army to clear out.
Bellamy steals one of the dead Ice Nation scouts' uniforms and is making his way across the field full of Azgeda warriors in the direction he saw Clarke last. He arrives at the subway station and finds Clarke tied up. They are briefly reunited before Roan has him pinned to the ground and is about to kill him when Clarke pleads for his life and promises Roan she will cooperate if he lets Bellamy live. Roan stabs Bellamy in the leg so he can't follow after them and takes off with Clarke again, leaving Bellamy behind. Bellamy still tries to follow after and is eventually found limping along by Monty. Kane and Pike try to get Bellamy to give up but he is worried about losing Clarke. Monty convinces Bellamy to head back and try again later.
In Ye Who Enter Here, Rover 1 pulls up to Mount Weather and Bellamy, Raven, Gina, and Octavia exit. Bellamy complains to Gina about not being at the summit because Kane is trying to teach Bellamy a lesson. They bring supplies into Mount Weather and enter the dining room on Level 5, finding it filled with Farm Station survivors, eating and having fun. Bellamy finds Octavia sitting on top of the side-door to Mount Weather. He asks her if she's okay and then climbs up to join her. She tells him that inhabiting Mount Weather is a mistake. Octavia reveals to Bellamy that once the kill order is lifted off Lincoln, they will finally be able to leave. She apologizes for not fitting in with the Sky People. Bellamy is understanding and tells her that she will always fit in with him. Two Farm Station survivors enter the clearing escorting a prisoner with them. Bellamy recognizes Echo, who has been taken captive for "threatening the summit." Bellamy and Octavia free her to the protests of the Farm Station guards and Echo tells them the summit is a trap and all of the Sky People will die. They bring Echo into the mess hall. Pike and Bellamy question Echo as other Farm Station members are grabbing weapons and arming themselves. Echo tells them the summit is a trap. Bellamy tells Pike they can trust Echo because she saved his life. Bellamy tells Gina to remain behind to help them find the launch codes while he leaves for Polis to warn the rest of the Sky People about the attack since they are not responding to the radio.
Bellamy, Octavia, Echo, and Pike arrive at the outskirts of Polis and park behind the truck Kane and Abby arrived in. Octavia discovers the two guards Kane left behind had their throats slit and that is why they did not respond when radioed about the threat. Pike starts to go after Echo but Octavia steps in and tells him that Echo warned them. Octavia tells Echo she is not leaving her blade behind before entering Polis and Echo says she will take them through the tunnels so they can keep their weapons.Under Polis, Bellamy, Echo, Octavia, and Pike move through the tunnels toward the elevator shaft to the Polis tower. Two guards spinning the wheel that raises and lowers the elevator are in their way. Pike and Bellamy attack and kill the two guards running the elevator. Octavia is upset that they killed the guards when they did not have to. Bellamy insists they did. They proceed to climb the ladder up the elevator shaft to the top floor. Octavia, Bellamy, and Pike barge into the throne room, holding a guard captive. Bellamy warns everyone the summit is a trap. Ivon, the Ice Nation representative, tells them it was the Skaikru who barged into the summit with guns. Pike says they are right because two Skaikru guards are already dead. Lexa asks how they came by the information and Octavia realizes Echo is no longer with them. Bellamy realizes Echo betrayed them as Kane tells him to stand down. Raven comes across the radio and tells them that the Grounders attacked Mount Weather and it is completely gone with only her and Sinclair surviving. Ivon tells them that is what they get for moving their people back into Mount Weather and the Ice Nation did what Lexa was too weak to do. Lexa declares war and orders the Ice Nation delegation along with Prince Roan to be arrested. Abby worries that Arkadia might be under attack next and Lexa commands them to go. Indra offers to escort them and tells Octavia she hopes she kept up on her training because she will need it before giving her back her sword. Bellamy tells Clarke they need to leave while Lexa offers Clarke protection if she remains as Skaikru ambassador. Clarke tells them she is staying to make sure Lexa keeps her word. Bellamy warns Clarke that Lexa will always put her people first and tells her to come home but Clarke apologizes and stays.
In Watch the Thrones, Bellamy stands outside the conference room when Pike opens the door revealing him. Bellamy walks into the room, Kane asks him why he isn't at his post, Bellamy returns his guard uniform, and Kane then asks him to take it back. Bellamy feels guilty and blames himself about the attack on Mount Weather and the death of Gina, and Kane tries to comfort him. Bellamy storms out of the room. Bellamy pays his respects and also speaks about Gina at the Memorial for the Farm Station victims killed in the Mount Weather destruction. After Gillmer hit Lincoln's head with a rock and chaos erupted, Bellamy helped stop the fighting and bring peace back to the memorial. Pike and Bellamy sit down and talk about Mount Weather, Pike confronts Bellamy, about the claims that the Mount Weather destruction was because of Bellamy, Pike then says it was Bellamy's fault but also his too. Pike tries to sway Bellamy to his side, by telling him biased facts about the grounders. Pike believes that he must take action quickly and he has the men ready for it. Bellamy finally comes to the conclusion that Pike wants him to get them automatic rifles and Bellamy then agrees to Pike's plan.
At night Bellamy, Pike, Gillmer, Hannah, and 6 others march to the front gates of Arkadia, there they are confronted by Lincoln, Harper and Monroe. Bellamy persuades Harper and Monroe instantly but Lincoln won't move. Gillmer quickly takes action, and raises his gun to Lincoln, Lincoln and Gillmer then engage in fighting. They quickly draw a crowd, Octavia, Abby, and Kane make their way up to the gate. Abby is appalled at Pike's actions, and Kane asks Bellamy if it was his decision to arm Pike's people. Abby then tells the guards to take the traitors to lock up including Bellamy. Pike stands up for his people, and Gillmer suggests that Pike should be one of the choices for the election. Abby ends the rally, and sends the traitors to lock up, as they exit the crowd starts chanting Pike over and over again. Kane then comes to lockup and tells Pike that he won the election. Pike then pardons all prisoners including Bellamy. As Bellamy leaves, Kane begs him to choose the right side, and Bellamy then says he already has.
In Hakeldama, Bellamy returns to Arkadia after massacring the grounder army. Being spattered in blood (not his own), his sister asks him if he's okay, to which he replies that he is. When Octavia asks him what happened, Bellamy remains silent and then proceeds to listen to Pike's speech.
Bellamy is present during the new Chancellor's war council in which Pike proposes to clear a 15 kilometre perimeter around Arkadia for farming purposes. When Bellamy points out that there is a Grounder village within that radius and appears concerned of Pike's determination to clear it, Pike asks the rest of his people to leave the room so he can talk privately with Bellamy. Pike offers Bellamy his guard jacket back, but Bellamy tells him they went too far by executing the wounded grounder warriors (something Bellamy tried to prevent during the time). Pike admits that the policy was severe, but justifies their actions by saying that they can't afford the wounded grounders recovering to fight again. Pike asks Bellamy to think about the people they potentially saved and not those they killed and Bellamy accepts this and takes his jacket back. Leaving the conference room, Bellamy is confronted by Kane and Lincoln, who try to convince Bellamy to see the error of his ways.
Pike has the sick grounder patients at Arkadia "interned", an action that leads to a confrontation between Shawn Gillmer and Lincoln. Bellamy tries unsuccessfully to defuse the situation and Lincoln proceeds to punch Gillmer to the ground. When Bellamy tries to get Lincoln off of Gillmer, he gets an elbow to the face. Lincoln eventually succumbs to arrest after Pike points a gun at Denae, one of the sick grounders.
While Lincoln and the other grounders are being sent to lock up, an outraged Octavia arrives, demanding to know what's going on. Bellamy informs her of the situation but she is furious at him for massacring the grounder force with Pike. Octavia then leads Bellamy to Clarke who has secretly entered Arkadia to talk with him. However, Bellamy is angry at Clarke for leaving her people and believes that she chose the grounders over them, he is further infuriated when Clarke arrogantly tries to tell him "it's over". Clarke tells him that justice was done, that Queen Nia of Azgeda is dead and that Arkadia must "make things right", or Lexa's coalition will wipe them out. After just being betrayed by Echo and previously being betrayed by Lexa, Bellamy doesn't believe peace with the grounders is possible and that if war is inevitable, Pike is the best man to lead the Arkadians. Clarke disagrees and is unable to see the situation from Bellamy's perspective, forgetting that besides from Lincoln, Bellamy has never been on good terms with any of the Grounders except when they had a common enemy. Bellamy harshly reminds Clarke about all the people that died while she was in charge, including the Mountain Men that helped them, and that she was willing to let a bomb drop on his sister. Clarke tearfully apologises and Bellamy replies, "I'm sorry too", before handcuffing Clarke to a table.
Bellamy and Gillmer retrieve Clarke with the intention of escorting her to Pike, but they are waylaid by Octavia who knocks out Gillmer. While Bellamy is distracted, Clarke seizes Gillmer's shock baton and stuns Bellamy with it, Clarke and Octavia then flee Arkadia.
In Bitter Harvest, Bellamy and Pike are walking through a corridor together when they are stopped by Kane, who wishes to discuss the chips Jaha is distributing and the interned grounders. Kane believes they should send the grounders back to their homes, but Bellamy disagrees, calling the grounders a "liability", as they have knowledge of Arkadia's defences and capabilities. Bellamy and Pike then continue on their way to the Chancellor's office for a meeting.
During the meeting, Pike outlines his plan to cultivate the land surrounding Arkadia and plant within the month. The issue of the grounder village in Sector 4 pops up again (as it is situated by the most fertile land), and Bellamy tries to tell Pike that the people there are not a threat. Pike nonetheless points out that they need the land or Arkadia will starve within a year. The people at the meeting, which include Hannah, her son Monty, and Zoe Monroe, then discuss the need to clear the village and Bellamy makes a final plea to Pike to leave the village alone. "What would you prefer?" asks Pike, "die fighting for your home, or starve to death?" Bellamy acquiesces and accepts that the villagers must be driven away.
While Bellamy and the rest of the village strike force gear up, Kane attempts to talk Bellamy out of it. Bellamy, knowing that Kane at least suspects what their mission is, tells him that that they're trying to build a future, not "trying to make peace with people who only understand war". Bellamy then climbs into the armoured personnel carrier, (APV), and then tells Bryan, who's talking to his boyfriend, to get in.
The armoured rover arrives at the village on a rainy night but the team find it deserted, after some hesitation, Bellamy signals for the Arkadians to move in and while searching the village they hear a rider approaching. Fearing it to be a grounder, the group take up defensive positions, but it turns out to be Octavia who yells at Bellamy to get his people out of the village as it's a trap. Just then, a small group of grounder archers shoot a volley of fire arrows into the village, igniting some poison sap traps which the grounders had set up. The smoke of the poisonous sludge is a deadly gas, something which Octavia also warns the group about. Bellamy immediately sounds the retreat and some of his soldiers attempt to hit the archers with rifle fire. The smoke spreads quickly and soon envelops Monroe and Lacroix, a member of farm station, who both succumb to the gas. Heroically, Monty charges back into the smog and is able to carry out Monroe, but it is too late, and Bellamy and the others watch helplessly as she dies.
Bellamy speaks privately with Pike, who asks him how he's holding up. Bellamy says he's been better and Pike tells him how his sister's actions cost the lives of two of their people and caused the soil to become poisoned by ash. Bellamy defends Octavia by saying she tried to warn them, but Pike points out that this was only after she warned the grounders first. Pike knows that Octavia must have been given intelligence from someone inside Arkadia, and both Bellamy and Pike easily deduce that it was Kane. Realising that he can't move against Kane without proof, Pike orders Bellamy to find some and then dismisses him.
In Terms and Conditions, Bellamy climbs to the top of an observation tower with Pike. There they meet Hannah at a radio station, where she informs them that they have lost contact with one of their recon teams while it was on a routine patrol. She tells them that the four-man team's last transmission was that they had been forced to engage hostile grounders. Hannah also says that two other teams also reported grounder contact less than a mile outside Arkadia but managed to get back to safety; Hannah concludes that the grounders are establishing a blockade. Chase, an Arkadia Guard on lookout duty in the tower, spots movement at a treeline which is revealed to be two grounders on horseback heading for Arkadia. Bellamy immediately recognises them as the messengers who had come to Arkadia several months ago demanding Finn Collins be handed over to them. Bellamy and Pike climb down from the tower and order the gates be opened, Bellamy tells the messengers to talk. The Coalition this time demand that Pike be turned over to them to face retribution for the destruction of the Trikru peacekeeping force. In return for handing over Pike, the grounders say they will leave Arkadia alone and stop the blockade. One of the messengers then throws a bundle of human remains at Bellamy's feet, it's the recon team, and the warrior remarks that it took them a long time to die and threatens any Arkadians who try to leave with the same fate. Pike, having heard enough, orders Bellamy back inside the gates, but Bellamy refuses. "Choose the side that's best for your people", one of the messengers says. "I do that every day", an angered Bellamy replies, and then sends a message of his own by drawing his pistol and killing both messengers with it.
In the Chancellor's office, Bellamy, Pike, Hannah and Monty discuss Coalition positions and the shortage of food within Arkadia – with rationing they will nearly be out of supplies in two weeks. Hannah suggests an attack on the blockade, but Pike is more concerned with Kane's insurrection and makes containing him a top priority. Pike orders Bellamy to lock down the prison section so that Kane has no contact with the grounder prisoners, and puts Monty in charge of camp-wide surveillance. When Monty expresses moral reservations about spying on their own people, Pike tells him that he knows that isn't what he signed up to do, but that it is necessary in order to find any traitors.
Later on, after Pike has inspected the armoury, he meets with Bellamy and Hannah to tell them that they don't have enough ammunition for the numerous firefights that can be expected during an extended siege. Bellamy asks about a plan B. Having located the largest grounder encampment in a valley, Pike proposes that they launch an assault with a team in Rover 1 to buy themselves some time. Hannah points out that the grounders can just retreat and regroup over a ridge, but Pike says that is part of the plan as he intends to mine that area before they attack. However, Pike has since found the listening device that was planted by Kane's people and he has meant for the whole battle plan to be overheard so he can catch the rebels when they try to compromise it.
Bellamy answers a radio call from Monty, who has been secretly following Kane. Monty informs him that he believes Kane is up to something and that Sinclair is probably part of his plan. Bellamy acknowledges this, and says they will keep an eye on Sinclair.
Bellamy walks into the vehicle bay where a suspicious-looking Kane is sitting reading a book while Sinclair works on the rover which was to be used in the supposed attack on the grounders. Bellamy asks Sinclair what he's doing; who replies that he is fixing the vehicle. Knowing nothing is wrong with the rover, Bellamy asks Sinclair for a work order which he knows he doesn't have. Sinclair, realising that he's been compromised, attempts to flee but is quickly apprehended. Bellamy places him under arrest for treason and then radio's, "that's one down".
Sinclair is taken to a private room to be questioned as to who he was working with. When Pike arrives, Bellamy says Sinclair hasn't said anything, so Pike places the listening device on the table and asks Sinclair about it; who denies any knowledge of the bug. Pike suddenly asks Bellamy for his gun. Surprised and a little concerned, Bellamy obediently hands over his weapon and Pike uses the butt of the pistol to smash the bug. Sinclair, aware of the threatening gesture, still refuses to give up any names, but Bellamy says he will talk eventually and suggests they put him in lock-up. Hannah calls Sinclair a traitor and implies that she believes they should execute him, but Pike refuses and has Sinclair imprisoned with Lincoln and the other grounders.
Bellamy meets with Kane in the vehicle bay and tells him that sabotaging the rover wasn't much of a plan, Kane doesn't deny the allegation and criticises Bellamy for spying on his own people. Kane believes that Pike is a bigger threat to their future than the grounders and tries to convince Bellamy of that, but Bellamy says that Pike's the Chancellor and tells Kane to "do the right thing". Kane all but admits to undermining Pike's leadership when he replies that however way he looks at the situation, he is doing the right thing. Bellamy accuses Kane of causing Monroe's death, and Kane believes that Sinclair will die next as Pike will probably execute him. Bellamy doesn't think Pike would kill Sinclair and Kane urges Bellamy to predict how the situation will end – with Arkadia starving and eventually turning on Pike, and then the grounders finishing them off. Kane says that Pike's policy of taking the fight to the grounders is what got Monroe killed and asks Bellamy to join him against Pike before it's too late, but Bellamy refuses.
After placing a bug in his boyfriend's pocket, Bryan meets with Bellamy and Monty and asks Bellamy if what he did was worth betraying Nate. Bellamy reassures Bryan that it was; since he did it to protect his boyfriend, but Bryan says that maybe Nate needed protection from him.
When arriving at the prison, Bellamy is informed by Chase that Sinclair is ready to talk. While Bellamy and Sinclair are discussing terms they are interrupted by Lincoln who says he will silence the traitor and then throws Sinclair to the ground and proceeds to beat him. Bellamy rushes into the prison to stop Lincoln but it is revealed to be a trick and Lincoln rushes Bellamy, knocking him against a wall and breaking out of the cell with the other grounders. The grounders begin to overpower the prison guards, but reinforcements arrive and suppress the insurrection. Monty, who has been monitoring radio signals, realises that the riot is a distraction and warns Bellamy that Kane is escaping Arkadia with Pike. Bellamy runs to the gate and gets there just in time to prevent Kane from getting out, holding him at gunpoint with a few other guards. Kane submits to arrest and Pike is freed.
Bellamy is present in the interrogation room when Pike decrees that he has the sole jurisdiction to sentence Kane. When given a chance to speak, Kane again urges Pike and his followers to change their views, but Pike remains intransigent and says that giving himself up to the grounders wouldn't bring peace. Pike then sentences Kane to death to the shock and dismay of Bellamy. Once Kane is taken away to the prison, Bellamy questions Pike's decision. Pike tells him that since they are at war, crimes against Arkadia's leadership won't be tolerated and he intends to make Kane an example. Bellamy reluctantly accepts this.
Bellamy meets with Monty, who asks him what to do about Miller and Harper, who they know were also a part of the rebellion. Before Bellamy can answer, Monty's mother interrupts and congratulates both of them for their apprehension of Kane; she then asks if they identified any other of Kane's associates. Perhaps afraid that Nathan and Harper would also be executed, Bellamy says they didn't. "It's not really that hard choosing what's best for your people is it?" says Hannah. "I do it every day", replies Bellamy.
In Stealing Fire, Bellamy visits the prison section with Pike. When Pike decrees that all of the prisoners will be executed for their part in the riot, Lincoln begs Pike to spare the other grounders and to only kill him, as he was their leader. Bellamy also advises clemency for the grounders and says that all they did was run through an open door, and that he would have done the same had their roles been reversed. Pike takes their pleas into consideration and reneges on his previous decision, deciding that only Kane, Lincoln and Sinclair will be executed. Pike then leaves, but Bellamy stays a moment longer to take a last thoughtful look at Lincoln and the others.
Bellamy and Monty meet with Nathan Miller and Harper in a cabin and carefully defuse the bug in Miller's jacket. Bellamy informs the duo of the impending executions and tells Miller and Harper that he and Monty want to help them in their plan to break Lincoln, Kane and Sinclair out of Arkadia in order to save their lives. Harper and Miller distrust Bellamy and deny that any plan exists. Not wishing to waste time, Bellamy just tells them to get a message to Octavia to meet him at the dropship in an hour.
Octavia shows up at the dropship riding Helios and glances around suspiciously, perhaps expecting a trap. Bellamy tells her he's glad she came and reassures her that he's alone and there to help. Octavia moves as if to embrace her brother, but sedates him instead.
Bellamy awakens chained to the wall of a cave with Octavia and Indra standing over him. Indra believes it was risky to bring him to their hideout and that Octavia should be in Arkadia helping the prisoners. Bellamy warns them that Pike's security has increased and that it's unlikely that she can get inside without being apprehended, he asks that they release him as his influence with Pike may be the only way to stop the executions. "You're the reason they need saving", Octavia tells him angrily. Bellamy admits that may be true but says Octavia still needs him, Octavia tells him that for the first time in her life, that's not true, and she leaves for Arkadia.
Bellamy appeals to Indra to let him go so that he can assist his sister, saying again that being trusted by Pike, he can help their cause. Indra reminds Bellamy of how he earned Pike's trust – by massacring her fellow warriors, and she asks him why he spared her on the battlefield. Bellamy replies that it's the same reason she hasn't killed him yet: because of how Octavia cares for both of them. Indra refuses to release Bellamy, much to his frustration.
While waiting, Bellamy and Indra hear a horn being blown, a worried Indra informs Bellamy that it means a new Commander has risen, meaning that Lexa must have died. Indra goes to leave for Polis and Bellamy accuses her of abandoning his sister, Indra tells him she considers Octavia as one of her own people, and asks Bellamy to tell Octavia she's sorry for leaving.
In Fallen, Bellamy is sitting alone in the cave when Miller, Harper, Bryan, Octavia, Sinclair and Kane enter after breaking the latter two out of Arkadia. Bellamy realises Lincoln is missing and is informed that he was executed by Pike. Bellamy tries to apologise to his sister, but distraught and furious, Octavia beats him till his face is a bloody mess. Kane and Miller both attempt to stop Octavia but Bellamy tells them to back off as he feels he deserves the punishment and his sister needs to vent her rage. "You're dead to me!" Octavia tells him when she's done, and Bellamy looks devastated.
Bellamy listens as the others discuss their situation. Bryan (who was persuaded by Miller to turn on Pike and join Kane's faction) is concerned that they may be too close to the grounder blockade, but Kane reassures him that if they stay away from the grounder lines, then they should be safe. The group then talk about the need to rid Arkadia of Pike, Kane is convinced that that is all it will take for the Coalition to lift the blockade and reinstall the Sky People as the thirteenth clan. Hearing this, Bellamy shakes his head in disbelief, mistrusting the grounder terms and believing Kane to be naive, but remaining silent. Sinclair is also sceptical of Kane's trust in the grounders, noting that with Lexa dead - as Bellamy previously informed them of the horns blowing and what they signified – how can they know that the new Commander will honour the terms. Kane avoids addressing that potentially problematic issue for the time being, and the conversation moves on to Clarke, who is effectively Skaikru's ambassador to Polis, with Miller suggesting that she may no longer be safe with Lexa dead. Knowing there is nothing to be done to help Clarke in their current situation; Octavia and Kane state their first priority is to assassinate Pike. At that moment Monty tries to contact Bellamy on his radio, Bellamy recognises a code phrase that Monty uses, which says to switch radio channels so that they can speak without being listened in on. Bellamy urges the group to change radio channels and answer Monty's message, Kane does so and Monty informs him that he is on the run because Pike knows he helped break the prisoners out of Arkadia. Kane instructs Monty to rendezvous at the 100's dropship and Harper warns him it could be a ruse by Pike. Octavia, fairly certain, (and hoping) that it is indeed a trap, proposes that they bring her brother along to trade for Monty if necessary. Kane, not wishing to put their whole group at risk decides that only he himself, Octavia and Bellamy will march to the dropship.
Cautiously approaching the dropship, Octavia senses something is wrong and holds her sword to Bellamy's neck, demanding that whoever is in the dropship to come outside. Monty emerges – with Pike holding a gun to his head, revealing that it was indeed a trap. Pike reveals that he isn't alone by having a sharpshooter put a shot at his rival's feet, ordering them to surrender, Octavia on the other hand urges Kane to shoot Pike, but Kane's line of fire is impeded by Monty, who Pike uses as a human shield. Kane, fearing for Monty, drops his gun, but Octavia stubbornly refuses to back down, so Pike radios his gunner to put a shot in Octavia's leg. Hearing this, Bellamy overpowers his sister himself to prevent her from being wounded, Pike signals his escort, which comprises of Shawn Gillmer and three other soldiers, to come forward and take the rebels into custody. Pike, somewhat mistrusting of Bellamy due to the suspicious circumstances of his capture, asks Bellamy to prove he is still with him. Bellamy immediately replies that he knows where the rest of Kane's allies are hiding in their cave and offers to lead Pike to them, much to Octavia's fury. Not having enough people in his escort to take the prisoner's back to Arkadia and to assault the hideout at the same time, Pike decides to take Kane, Octavia and Monty with him as he follows Bellamy to the remaining rebels.
Trudging through the forest, Pike question's Bellamy's route and is concerned that it is taking them too close to the blockade line. Bellamy simply explains that is the point, as Kane hoped the close proximity to the grounders would prevent any of Pike's search party's from finding them. Bellamy negotiates with Pike and is able to grant his sister immunity from any punishment for her crimes. Pike begins to warn Bellamy of what might happen if Octavia should get into trouble again, but Bellamy cuts him off saying that she won't. "My sister, my responsibility", Bellamy reminisces.
Advancing further towards the grounder's boundary, Pike becomes ever more wary, but Bellamy is able to convince him to carry on. Suddenly, a war horn sounds - as Bellamy has intentionally walked the group to the grounders. Pike attempts to order a retreat, but Bellamy seizes his sidearm, and pointing it at Pike's head, demands that he drop his weapon. Gillmer moves to intervene, but Octavia knocks him to the ground, while the remainder of Pike's escort are too stunned (or useless) to do anything to save their Chancellor. Bellamy has Octavia translate a message to the grounders, saying that he has brought them Pike in exchange for them lifting the blockade. Grounder archers kill Pike's three standing soldiers and surround the group. Octavia, seeing her chance for retribution, picks up a knife and attempts to kill Pike, but Kane stops her, saying Pike needs to face grounder justice. Pike, hearing this, advances on Bellamy, but takes an arrow to the shoulder and is then beaten unconscious by the grounders. Kane asks to accompany the grounders to Polis with the captured Chancellor, but before he leaves, he asks Bellamy why he turned Pike over: for his sister's sake, or because he believed it was the right thing to do. After Kane's departure, Monty informs Bellamy that it was his mother that turned him in, Bellamy reassures Monty that he will work things out with his mother because they are family. Meanwhile, Gillmer regains consciousness, but Octavia stabs him in the chest and kills him, saying the grounder words for, "blood must have blood".
In Nevermore, back in the cave hideout, Bellamy is no longer a prisoner of the rebels after assisting them in the apprehension of Pike. The group receive a radio call from Jasper who tells them Arkadia is not safe and that he is on his way to the cave in a rover. While discussing Jasper's surprising message with Sinclair and Monty, Bellamy notices Octavia begin to pack supplies with the intention of leaving to recover Lincoln's body. Bellamy counsels his sister that she shouldn't go as Arkadia isn't safe, but Octavia believes Jasper's transmission sounded insane and still resolves to depart. When Bellamy asks her what more he has to do to earn back her trust, Octavia scornfully tells him to "bring Lincoln back", and angrily expresses to her brother that she knows he only turned Pike in to save her, not because he disagreed with the Chancellor. Bellamy defends Pike's policies against the grounders, saying the army that was massacred could have turned hostile and accusing the Coalition of besieging Arkadia. Octavia tells Bellamy that his sense of loss over his girlfriend and the other people they have lost caused him to "lash out" and consequently get more people killed. Octavia goes to leave but at that moment, Jasper arrives at the cave entrance in the rover with Clarke and an unconscious Raven Reyes. Bellamy inquires to whether Jasper was followed; Jasper responds that he doesn't know and urges the group to get Raven in the cave before she awakens. Clarke convinces Octavia to stay with them and the group enters the cave, Jasper explains the situation: Jaha is distributing "chips", that when swallowed causes the recipient to lose their memories and see a strange woman named A.L.I.E., Jasper continues by explaining that when someone has been chipped, A.L.I.E. can control them and that Raven was working on destroying her chip by using one of the delinquents old condition monitoring wristbands. A.L.I.E., however, had Jaha and her other minions destroy the wristbands and forced Raven to cut her own wrists. Upon hearing this, Clarke shows Jasper the Flame asking if Jaha's chips look the same, Jasper replies that they are not exactly identical. At that moment Raven wakes, sees the Flame and then flees from the cave. The group pursue Raven and are able to sedate her before she is able to inform A.L.I.E. of her location, regardless of this, Clarke says they all must leave because she knows where they can obtain a wristband.
Leaving Miller, Bryan and Harper at the cave, Clarke directs the rest of the group to a grounder trading post run by Niylah. When the group arrive Niylah is not pleased to see the Sky People due to the fact that her father was one of the grounder warriors killed by Pike's men during the massacre. Niylah refuses to grant Clark access to her home so Bellamy threatens her with his firearm while the others take Raven inside to the bedroom and restrain her as she wakes up again. With Raven contained, Clarke comes to explain the situation to Niylah and Bellamy gives them some privacy, though he remains suspicious of the grounder. Eventually, Niylah leaves to retrieve a wristband from her stores and Clarke asks Bellamy if he is okay, realising that he will be feeling guilty over the part he played in the death of Niylah's father, but Bellamy replies that he is fine.
Having obtained a wristband, Bellamy and Clarke question Monty and Sinclair on how Raven was planning on destroying her chip. They explain that the wristband could be used to generate an electro-magnetic pulse (EMP), to destroy the circuitry of A.L.I.E.'s chip, but that an electro-magnet is required. Knowing they can get an electro-magnet from the delinquent's dropship, Monty and Octavia take the rover to go salvage it.
When Raven dislocates her own shoulder and begins to get free, Jasper calls for aid and Bellamy and Clarke help to restrain her. Jasper, speaking to A.L.I.E. through Raven, discovers that A.L.I.E. wants to possess the Flame, which is her version 2.0. Clarke threatens to destroy the Flame if A.L.I.E. harms Raven; consequently, Raven ceases her struggling and allows Clarke to reset her shoulder. Bellamy warns Clarke that while Raven is under A.L.I.E.'s control, she will never stop trying to get away. Subsequently, it is decided that someone has to keep a watch on Raven at all times and Clarke volunteers for the first watch, to which Jasper yells angrily at Clarke that she doesn't give the orders; as he still hasn't forgiven her for the death of Maya. Bellamy orders Jasper from the room and then follows him out.
Jasper asks Bellamy if he is okay with Clarke coming back after what she did at Mount Weather and then abandoning them: Bellamy defends Clarke by saying that she just wants to save Raven. "Guess she thinks Raven is worth saving", a scornful Jasper replies. Bellamy tells Jasper to pull himself together and to not let his anger get in the way of what they need to do, but Jasper throws it back in Bellamy's face by reminding Bellamy of what his own anger caused him to do to the grounder army.
Bellamy enters Ravens room when he hears Clarke yelling at Raven. Clarke, having let A.L.I.E. get to her, is herded from the room by Bellamy.
Outside the room, Bellamy tends to Clarkes arm, which was bitten by Raven. "I let her get to me", admits Clarke. "You don't say", replies Bellamy as he wraps a bandage round her arm. Bellamy advises Clarke to take a break while he goes to babysit Raven.
While Bellamy and Jasper are watching Raven, she begins to taunt them and eventually provokes Jasper to an angry outburst after mentioning Maya. After Bellamy dismisses Jasper, Raven continues speaking to Bellamy, reminding him of the people who died because of him in Mount Weather and the culling. Raven even tells Bellamy his mother died because of him and calls her a whore, but still Bellamy doesn't break, although he endures Raven's monologue with obvious discomfort. Raven goes on about Gina and how Bellamy ‘avenged' her by being a part of Pike's massacre of the grounder army. Unfortunately, this latter part is overheard by Niylah who rushes into the room and punches Bellamy in the face for his part in killing her father. Clarke and Jasper sweep into the room to remove Niylah, but the group realise that it is too late and with Raven having seen Niylah, A.L.I.E. knows where they are. Bellamy, furious that A.L.I.E. was able to get the better of him and believing that much of what Raven told him was true, grabs his coat and heads outside to blow off some steam.
Bellamy vents his rage outside and Niylah confronts him. Bellamy eventually apologises for his part in the death of her father, "people like you always are", Niylah says. At that moment, Monty and Octavia arrive in the rover with the part they need for the EMP, and Bellamy immediately realises that Monty is upset about something.
The group converge at Raven's bedside and Sinclair and Monty begin to set up the EMP device. Upon seeing the device, Raven begins viciously bashing her head on the bed frame and Bellamy realises she is trying to kill herself before the group can disconnect the chip. While the group hold Raven down, and restrains her head, Bellamy is able to get the wristband on Raven's arm, but when they try to activate the EMP nothing happens - Sinclair informs them that the battery isn't strong enough. Monty and Bellamy run outside to get the rover's battery and one of A.L.I.E.'s drones appear which Bellamy promptly shoots down. They rush the battery inside and use it to fry A.L.I.E.'s chip, but Raven passes out.
While Clarke is distracted tending to Raven, Jasper seizes the Flame with the intention of smashing it, believing it to be just as malignant as A.L.I.E., but Clarke stops him by telling him that Lexa's consciousness is inside. Clarke then remembers how Titus removed the A.I. from Lexa's neck and proceeds to do so with Raven, revealing broken pieces of the chip in Raven's blood. Raven wakes up after the chip is removed from her system and Monty realizes that he could have saved his mother, instead of killing her. Bellamy reminds the group that A.L.I.E. knows where they are and that they have to leave.
Outside as they are about to embark on the rover, Bellamy questions the decision he made to side with Pike and asks Clarke what you do when you don't think you are one of the good guys. "Maybe there are no good guys", Clarke tells him. Putting Raven in the rover, Clarke asks her why A.L.I.E. wanted her to kill herself. Raven answers that it is because she knows that the only thing that can stop A.L.I.E. is the Flame, and that is why A.L.I.E. wants it.
In Demons, Bellamy is driving the rover while the group discusses Becca's diary (which Clarke had brought with her from Polis) and the need to find Luna, the last nightblood, so that she can merge with the Flame (A.L.I.E. 2.0) to help them stop A.L.I.E. 1.0. In order to find Luna, the team need to retrieve Lincoln’s diary from Arkadia. As the rover nears Arkadia, Bellamy warns the others to stay alert and then attempts to contact Miller, Bryan and Harper via radio, but there is no reply.
The group arrive at Arkadia but find it deserted; Bellamy again tries unsuccessfully to contact their missing people. As they move further into the camp, the group comes across a blood stain on the ground and everyone realises that it is the spot where Lincoln was executed. Octavia, upon seeing the blood, just tells the others to find Lincoln’s book and to get out of the place. The rover is driven into the hangar bay and Bellamy orders it to be turned around in case they need to make a quick getaway. The area looks as if people simply stopped what they were doing and left, Bellamy orders everyone to load the rover up with supplies and to find Lincoln’s book as quickly as possible.
Bellamy searches the armoury, finding there are still plenty of guns and ammunition, then radios for the others to join him.
While waiting for the others to join him outside at the armoury, Bellamy sees Clarke running towards him in distress. Bellamy asks Clarke what is wrong and she replies in one word: Emerson.
With his weapon at the ready, Bellamy leads Clarke through a hallway in Arkadia and asks her where Monty is - Clarke replies that Emerson took him but doesn’t know why. Bellamy tries to contact his sister and Jasper, but receives no response; he and Clarke conclude that Emerson probably has them too, as well as Harper, Brian, and Miller. Clarke feels that the situation is all her fault and tells Bellamy of how she had a chance to kill Emerson in Polis but let him go. Hearing Bellamy’s radio call, Raven contacts him, asking what is wrong and Clarke informs her of the situation and tells her and Sinclair to lock down the hangar bay.
Arriving at the hangar bay, Clarke and Bellamy immediately realise that something is wrong as the power in the hangar bay has been disabled and the sounds of a scuffle are heard inside. Unable to get through the inner doors to the hangar bay, Bellamy and Clarke head around to the outer doors. Entering the hangar bay, the pair sees a body on the ground which is revealed to be Sinclair: who has been stabbed and killed by Emerson. Raven has also been captured by Emerson. Bellamy and Clarke deduce that Emerson is holding their people somewhere and guess that that place may be the airlock where Emerson himself was once imprisoned. Knowing Emerson will by now have one of their radios, Clarke contacts him, offering to turn herself over to him in return for letting her friends go. Emerson accepts Clarke’s offer and demands that she shows herself at the airlock with no weapons. Clarke attempts to give Bellamy the Flame as she fully intends to let Emerson kill her in order to save her friends, but Bellamy tells her it is a stupid thing to do and suggests instead that Clarke should distract Emerson so he can shoot him.
Clarke approaches the airlock while Bellamy hangs back around the corner of the hallway. Clarke demands that Emerson release his hostages, but Emerson says that he won’t until Bellamy shows himself first. When Clarke tries to deny that Bellamy is with her, Emerson beats Octavia to make Bellamy show himself and then orders him inside the airlock while threatening to cut Octavia’s throat. Bellamy disarms and enters the airlock despite Clarke telling him not to, Emerson then prompts Bellamy to handcuff himself to the wall. Emerson gets Clarke to kneel and he then exits the airlock and closes the door. Grabbing Clarke and pushing her against the glass of the airlock door, Emerson tells Clarke that he intends to kill her friends in retribution for all of his people who she killed at Mount Weather and she is going to watch them die – Emerson then pushes the button to vent the oxygen from the airlock. Bellamy and the others inside gradually begin to succumb to suffocation and lose consciousness. Clarke however, is able to implant Emerson with the Flame, which kills him as his blood isn’t compatible with it. Clarke then opens the airlock door and saves her people.
Having survived Emerson, Bellamy finds Lincoln’s body and carries it to the rest of the group outside the walls of Arkadia. Octavia mourns over Lincoln’s body and Bellamy accepts that he was partly responsible for his death. The group build a funeral pyre for both Lincoln and Sinclair and burn their bodies together. Octavia gives Bellamy a long, cold stare and then tells the others it is time to go and that she will retrieve the map which shows the way to find Luna.
Bellamy finishes loading the rover and then asks why Raven isn’t ready. Raven replies that she is staying in Arkadia to analyse A.L.I.E.’s code (which was previously downloaded into the ark mainframe) and that she may be able to find a ‘backdoor’. Miller, Harper, Bryan and Monty also opt to remain in Arkadia to assist Raven, while Jasper chooses to accompany Bellamy, Clarke and Octavia to find Luna.