In Echoes, in the aftermath of A.L.I.E.'s demise, Echo holds Clarke Griffin at swordpoint when King Roan is found gravely wounded. She doesn't trust the intentions of the Sky People who she blames for bringing A.L.I.E. to the grounder capital, causing the death of Ontari, and stealing the Flame. She wants the king tended by Azgeda's own healers. After Bellamy appears and demands that she let Clarke go, Echo thanks Clarke for destroying the City of Light and releases her. Echo takes charge of the Azgeda army which is occupying Polis and declares the city to be under Azgeda rule, this is immediately contested by the ambassador of the Boudalan clan. Echo declares herself in charge while the king is unconscious and kills the ambassador on the spot.
Echo is watching over King Roan as the healers are at work when Thelonious Jaha brings her the supposed body of Ontari. Recognizing Jaha as the leader of A.L.I.E.'s Cult she has him beaten by her guards until a messenger arrives with the news that Skaikru wishes to surrender. Echo takes Jaha outside and tells him to fetch Bellamy, as she will only talk to him. Once Bellamy arrives she reminds him that she saved his life by taking him out of Mount Weather before it was destroyed, but apologizes for not saving his girlfriend Gina Martin. They discuss surrender terms, Echo unaware that the meeting is a sham so that Clarke and Abigail Griffin can heal Roan. When Echo tries to leave the meeting, Bellamy moves to stop her and she responds by throwing him to the ground and holding a knife to his throat, demanding Skaikru drop their weapons, which they do. Echo returns to the King's chamber and discovers the intruders, but as she is about to execute Clarke, Roan regains consciousness and stops her from doing so. She advises him to kill Wanheda and lead Azgeda to take over the Coalition.
After Clarke and her allies are imprisoned while Roan makes his decision, Echo comes to Roan and again advises him towards war with Skaikru and Trikru, and the execution of Clarke, saying that his people need to respect him. She then presents him with his grandfather's crown. Echo fetches Clarke from the dungeons and presents her to the King, asking if she should summon the war chiefs, but Roan tells her to get out, as he wants to talk with Clarke alone.
Echo stands guard as Roan gives his speech accepting Skaikru as the 13th clan and declaring himself Caretaker of the Throne and Keeper of the Flame. Afterward, she presents the King's seal to Bellamy. She asks him if they will ever trust each other again, to which he replies, "I doubt it."
In Heavy Lies the Crown, Echo leads King Roan to his throne room and informs him that she has doubled the Azgeda guard on every floor. She questions his decision to rule as Lexa did by keeping the Coalition together, but before he can answer, Marcus Kane and Octavia Blake enter, and Roan orders Echo to leave.
Later, she spars with Roan and offers to take his place in single combat if Trishanakru challenges him. Roan refuses this offer and tells Echo he will not run from the challenge. Echo asks what Wanheda offered him and Roan tells her of the impending nuclear apocalypse and Skaikru trying to stop it. Echo doesn't think the story is true, believing it to by a lie invented by the Arkers so that Roan doesn't attack them. She immediately asks to sneak into Arkadia herself and discover the truth, but Roan commands her not to go until after his fight.
During the ambassador meeting, Echo enters and informs Roan that Ambassador Rafel has been found dead.
Echo goes to spy on Arkadia and realizes that Skaikru are repairing Alpha station to survive the radiation. She considers this as a betrayal of the agreement between Arkadia and King Roan, as only Sky People will be saved from the nuclear storm. In retribution, Echo captures Bellamy and Stevens who are out hunting, interrogates them and then returns them to Roan as hostages.
In A Lie Guarded, when King Roan confronts Kane about what is being done to stop the apocalypse and is not satisfied by his answers, Echo enters with Bellamy and Stevens. When Kane explains the plan to turn everyone into Nightbloods (as they can survive very high radiation levels), Echo calls it blasphemy and tells Roan, "nothing they tell us is true". Roan distrusts Kane also and gives the nod to Echo who pulls out a blade and slits Stevens' throat, saying with disgust that warriors don't reveal their secrets. The King then declares war on Skaikru and Trikru and orders Echo to find Octavia and Indra and kill everyone else, Echo leaves, looking pleased to have finally gotten her way.
Echo tracks Octavia to the outskirts of Polis and pursues her on horseback with two other Azgeda warriors. Octavia, riding her steed, Helios, eventually becomes cornered on the edge of a ravine and dismounts. Echo demands Octavia come quietly and tells her that Roan wants her alive, Octavia resolves to fight. Echo orders one of her warriors, an archer, to shoot Octavia in the leg, but Octavia kills the man with a throwing knife. Echo and her remaining warrior then dismount and engage with their swords, but Octavia proves to be more than a match for them, wounding Echo in the leg and killing her remaining warrior with a vicious backhand blow. Echo and Octavia then continue to duel, with Octavia's back to the cliff. Eventually, Echo gains the advantage over her exhausted opponent and breaks Octavia's sword before knocking her to the ground. Even then, Octavia doesn't give in, picking up the sword of the warrior she had just killed and charging back at Echo. The move takes Echo by surprise and she raises her blade to defend herself, accidentally impaling Octavia with it. Echo pulls the sword free and then looks on, shocked and seemingly horrified as Octavia tumbles backward over the cliff and into the river below. Echo peers over the edge but can see nothing in the rapids, and then respectfully says the grounder words that follow the death of a warrior.
Back in Polis, Echo enters Kane and Bellamy's cell with Roan and his guards. The king tells the prisoners they are coming with him and that he intends to take Arkadia and use it as a safe haven for his own people. Bellamy warns Roan that his sister will get to Arkadia first and warn Skaikru, to which Echo shows him the broken parts of Octavia's sword. Realizing that this could only mean his sister is dead, Bellamy starts to break down with grief and Echo tries to console him by saying that Octavia died a "good" death.
In The Tinder Box, Echo accompanies King Roan and his army on their way to Arkadia. While passing through a canyon they spot Clarke ahead and Roan implies that it means Octavia must have survived and warned Skaikru, but Echo tells him that it can't be true, still believing Octavia to be dead. After Roan orders his archers to target Wanheda, Echo warns him of the laser markers aimed at his chest, and it is revealed that there are Skaikru soldiers with rifles on the cliffs to either side of them. Roan gestures to Echo and she orders that their prisoners Kane and Bellamy be brought forth, placing them in front of the army on their knees to act as hostages. Clarke asks for Roan to meet her in private and he obliges, dismounting his horse to go and meet her. Echo warns the King that it could be a trap, but Roan simply replies that it is a trap and they're already in it, before walking away. Echo is left in command of the army and orders it to be ready should the Arkadians attack and to "kill till there's no one left". Kane tells her that since his people have thousands of bullets, the Azgeda army will be the ones with no one left, "then let's hope no one shoots", Echo replies coldly.
While they are waiting, one of the Sky people, Monty Green, appears in the bottom of the valley saying that he's unarmed and needing to speak with whoever is in command of the Azgeda forces. One of the grounders hustles him over to Echo and shoves him to the ground in front of her. Monty warns Echo that an Arkadian soldier, Riley, has deserted his position with the probable intention of assassinating King Roan. Echo regards this news with suspicion but is convinced by Bellamy that Monty isn't lying and that he's trying to stop a massacre. Echo orders two of her archers to accompany her and moves to leave, but is advised not to take the Warriors by Kane and Monty who tell her that the Skaikru snipers will open fire if they see the archers on the move. An alternate course is decided whereupon Bellamy alone accompanies Echo. After using Monty's radio to inform the gunners to let Bellamy and Echo past them, Echo keeps Monty as a hostage in Bellamy's place, and then heads off to locate Riley.
Bellamy, still chained at the wrists, leads Echo through the forest to where he believes Riley would have positioned himself. "Are you really willing to kill your own man to save my King?" Echo asks; Bellamy, in turn asks her if she gets sick of sides, reminding her that radiation doesn't care which side you're on - implying that everyone should be working together towards a solution to the apocalypse. Echo, finally accepting that Octavia must have survived, tells Bellamy she's glad he will be able to tell his sister goodbye before the nuclear storm. "If you'd killed her, these chains would be around your neck", Bellamy warns her. "…war makes murderers of us all", Echo remarks in reply.
Getting close to where they believe Riley is stationed and not wanting Echo to provoke him into firing his gun, Bellamy tells Echo to follow his lead, which she grudgingly accepts. The pair finally comes across Riley, who is lying prone with his sniper rifle trained on the entrance of the cave where Roan and Clarke are meeting. Bellamy immediately starts trying to convince Riley to stand down, while at the same time having to prevent Echo from killing Riley with her bow. "War made me a murderer", Bellamy tells Riley, "don't let it happen to you". After a tense moment when Riley takes Roan in his sights, he finally stands down.
Having sent Riley back to the Sky People, Echo and Bellamy meet Roan and Clarke. Surprised to see Echo and Bellamy in the forest away from his army, Roan asks what has happened, but Echo decides not to tell him of his would-be assassin and tells him everything is fine. Roan informs Echo and Bellamy that they are not at war (yet) and that they've come to an arrangement to share Alpha Station should the Nightblood solution fail. However, as fate would have it, at that very moment the group spots smoke coming from Arkadia and they realize something is badly wrong.
Echo, Roan and some of their warriors, together with the Arkadian forces, hurry back to Arkadia to find it engulfed in flames and being evacuated. Echo watches with hopeless amazement as Arkadia burns and the great ring of Alpha Station collapses to the ground.
In We Will Rise, after the forthcoming nuclear apocalypse has become common knowledge, King Roan sends Echo back to Polis with the bulk of his army to keep the peace. However, Roan mentions that more than half his warriors have deserted to be with their families in what may be their final weeks alive.
In God Complex, it is mentioned that Echo's troops are battling with Indra's Trikru Warriors for control of Polis. Echo's forces control the Flamekeeper's temple and the surrounding districts, while Trikru is holding the tower.
When Indra kills several Azgeda Warriors to capture the inner temple, she warns the small group of Sky People accompanying her that Echo will soon send reinforcements.
In DNR, King Roan is returning to Polis (after previously assisting Clarke and other Sky People at Becca's lab), when he is betrayed by Kane – who has renewed his alliance with Trikru. Three Trikru Warriors move to attack Roan but are ambushed by Azgeda archers under Echo’s command, who have either changed upon the King or have otherwise gauged his location from an unknown source. Kane, Clarke and the other Sky People present are all captured and Echo welcomes her King back to the capital.
When Roan arrives back in the city he immediately holds council with Echo to learn of the current situation. After Echo commands one of her warriors to keep the Skaikru prisoners well-guarded, she seems about to object when Roan orders that Clarke be brought to him, but she holds her tongue. Echo informs Roan of the alliance between Skaikru and Trikru and that they chose to capture the Flamekeeper’s temple, despite it resulting in the loss of the more strategically important Polis tower. Echo, realizing that the temple must be of some importance, explains that she ordered the Azgeda forces to besiege and blockade the temple. Roan praises her, saying she has done well. Clarke arrives and Roan dismisses Echo so he can speak with Clarke alone.
It is revealed that the temple houses a bunker capable of housing over 1000 people from |Praimfaya, so Roan attempts work out a truce with the Trikru alliance, but the negotiations fail. Echo and Roan discuss their plans for assaulting the temple but are interrupted by the ‘ascension call’, which only sounds when a new Commander is about to take the Flame. Echo asks how ascension is possible considering the Flame was destroyed, and Roan realizes that he was deceived into believing that the Flame was gone. Echo advises that they try to stop the ascension until they learn who the Nightblood is, but Roan replies that he already knows.
In the throne room, Roan prevents Clarke from ascending and calls for Echo to enter the room with “the healer”, (Clarke’s mother, Abigail Griffin). Roan has Abby inform the ambassadors that Clarke is a fraud, having only become a Nightblood through science. Roan goes on to say that this means they can no longer trust ‘the blood’ if science means that anyone can become a Nightblood and take the Flame – at this, Indra replies that they can still trust the sword and resolves to continue the war. Indra goes to leave, but Roan stops her and offers an alternative, less bloody, solution. Roan proposes that each clan offers up a champion to fight in a Final Conclave, the victor to be rewarded with the bunker for their own people. Indra and all the other ambassadors agree to the conclave.
In Die All, Die Merrily, Echo is present in the crowd which is spectating the champions of each clan being announced by Gaia and each receiving a necklace bearing the sigil of their clan. Among the chosen warriors are: King Roan, Octavia Blake, Ilian and Fio. Gaia gives a speech outlining the rules of the conclave but is interrupted by Luna, the last member of Floukru, who demands the spot of the thirteenth champion. Gaia questions Luna as to who she is fighting for seeing as the rest of her clan are deceased and Echo and everybody else are shocked when Luna declares that if she wins then no one will get the bunker and she’ll leave everyone to perish in Praimfaya.
After the champions have been sworn in, Echo meets with Roan and they are both approached by Clarke, who asks to speak with Roan alone. For once, Roan doesn’t dismiss Echo, and simply asks Clarke what she wants. Clarke states that they can’t let Luna be victorious and implies an alliance, but Roan states that the time for alliances has past. When Clarke asks Roan if he can defeat Luna, Echo states he can, saying Luna “bleeds like everyone else”. Roan tells Clarke she has no respect for grounder traditions and that if he is killed in the conclave then he doesn’t care who, if anyone gets possession of the bunker. “See, that’s the difference between you and me Roan”, Clarke replies, “I want humanity to survive, even if it’s not my people”. Roan harshly advises Clarke to: “get off this battlefield before you dishonor your people once again”.
Once the conclave commences, Echo goes to the throne room with the other ambassadors, advisers, and leaders, and waits anxiously to find out if Roan has been killed when it is announced that the first two warriors have fallen. It is revealed, that the killed warriors are Fio and Gael.
Unable to resist the urge to assist her King, Echo takes a bow and sneaks out of the throne room into the city. Echo then secretly kills the Blue Cliff champion and steals her mask before shooting dead the Sangedakru champion from a window.
Later, Echo remains indoors and hears the sound of a fight. She makes her way toward the sound and observes Ilian and Octavia defeat three other champions. Having a clear shot at Ilian, Echo puts an arrow through his neck but is unable to hit Octavia, who ducks behind cover while dragging the mortally wounded Ilian with her.
As night falls, Echo is perched in a high window and just about to shoot Octavia when she hears the door behind her creak. Instinctively, Echo whirls around and lets loose her arrow, but she misses and her assailant smashes her into the wall and throws her to the floor. Echo’s attacker turns out to be Bellamy, and he whips off Echo’s mask and proceeds to strangle her. Echo is only saved by Roan, who enters the room and kicks Bellamy off of her, saying that he heard both of them, “all the way down the street”. Bellamy informs Roan that he only came into the city to stop Echo, and Roan demands that Echo explains what happened. Echo admits to Roan that she was trying to help him to win the conclave, and Roan is disgusted to have such an affront to his honor as having a cheater on his side. Roan then takes the drastic measure to banish Echo from Azgeda and states that if he wins the conclave then she will not have a spot in the bunker. Echo then leaves in disgrace.
Back in the throne room, Echo is devastated when it is announced that Roan has been killed. Octavia, having slain Luna, enters soon after with the clan sigils and is announced victorious by Gaia. Octavia then declares that she will share the bunker evenly between all the twelve clans and that each clan must choose 100 people who they wish to save.
In The Other Side, Kane is helping the clans select the people who they wish to send to the bunker, but Echo suspects he is stalling and sneaks into the Flamekeeper’s temple to investigate if something troublesome is occurring. Inside the temple, Echo eavesdrops on Octavia and Indra and learns that the entrance to the underground shelter has been locked from the inside by Skaikru: who secretly stole the bunker for themselves before the conclave had even ended. In order to keep the peace, Octavia, Kane and Indra have decided to hide the truth from the grounder clans and hope they can resolve the matter before any of them find out about the betrayal. Echo confronts Octavia and Indra and threatens to reveal their secret to the clans, saying they will pay for it “in blood”. But as Echo turns to leave, Octavia counters Echo’s threat with one of her own, saying that she knows King Roan banished Echo from the Azgeda for cheating during the conclave and that it would be easy to prove it by having the Flamekeepers check the Blue Cliff champion’s body for Azgeda's arrow wounds. Hearing this, Indra states that Azgeda shouldn’t have a place in the bunker, but Octavia disagrees and replies that she will not banish an entire clan because of the actions of one person. Octavia tells Echo to wait with her and Indra for Bellamy to open the bunker from the inside. Realizing that she has no choice, knowing that Bellamy will never leave his sister to die, and no doubt recalling Bellamy’s actions during Mount Weather, Echo agrees to Octavia’s plan.
While waiting at the bunker hatch, the trio begins to feel the effects of the increasing levels of radiation. Eventually, a temple priest enters the room and informs them that the black rain (which was until that moment keeping the clans from approaching the temple) has now stopped and that the grounders are approaching. The priest asks if they should try and stop the clans from entering, but Octavia tells him to let them in, “it’s time to face the music”, she says.
Just before the clans start to arrive, Bellamy is able to open the hatch, much to Octavia’s relief. Octavia then addresses the clan leaders, announcing that they are now one clan and that the bunker is their new home. Suddenly, Octavia snatches Indra’s sword and holds it to Echo’s throat – “everyone except you”, Octavia declares. Echo reminds Octavia they had a deal, but Octavia replies that although she promised to save Azgeda, she didn’t say anything about saving her. Echo shows the fear on her face and glanced hopefully at Bellamy but to no avail. Octavia whispers to Echo that she is free to inform the clans about Skaikru’s hijacking of the bunker, but that since the door is now open, such a claim could easily be discredited. “Be thankful knowing your banishment will be short”, gloats Indra. Echo puts on a brave face and states simply that, “praimfaya awaits”, before she leaves the temple.
In The Chosen, she secretly follows Bellamy Blake, Clarke Griffin, John Murphy and Emori who were on their way to save Raven Reyes. When Bellamy runs of a grounder with the Rover causing them to crash into a tree, then some grounders attack the group and Echo comes out of hiding, riding a horse and helps them fend off the grounders by shooting them with arrows. Bellamy and Clarke are surprised to Echo and ask her what she's doing. Echo says, "I know about the bunker on the island, I just saved your lives and I was hoping you'd return the favor". Clarke and Bellamy agree and she goes to the Becca's Island with them.
In Praimfaya, she helps the others get the rocket ready before trying to commit suicide. Bellamy stops her and convinces her to come with them. She goes to the Go-Sci ring with the rest.