In Inclement Weather, Octavia and Indra first meet when Octavia tries to bargain with Indra by swapping Nyko, the clan's healer for Lincoln, who the grounders have captive. Later Indra and Octavia make the swap but are interrupted by a band of Reapers who take Lincoln and Nyko captive.
In Reapercussions, Octavia urges Indra to let her help search for Lincoln and Nyko. When Indra orders her death, Octavia runs from the Grounders and hides. Later, Octavia continues to follow Indra and her group as they search for Nyko and Lincoln. When Indra reveals that Octavia will be the bait for the Reapers she announces that she is not afraid. Octavia helps Indra and the other Grounders fight off the Reapers and at one point, Artigas saves her life. When Indra is defenseless, Octavia saves her by killing the Reaper who would have killed Indra. Once the Reapers are taken care of, Octavia discovers from Nyko that Lincoln is not among the freed Grounders. When she doesn't find him she screams out in anguish.
In Long Into an Abyss, Indra witnesses Octavia's devastation over Lincoln's momentary demise. She gets ready to attack the Sky People before Abigail Griffin is able to bring Lincoln back.
In Remember Me, while camping for the night, Indra mutters "natrona" (traitor) to Lincoln, much to his displeasure. He is then comforted by Octavia who wants to help him recover emotionally from his Reaper experience. When Gustus is poisoned at the alliance banquet, all the grounders lock up the Sky People to determine who it was. Octavia asks Lincoln to intervene on their behalf, but Indra says he is one of the Sky People now.
In Survival of the Fittest, Octavia attempts to get Indra to let her train with the grounders, but Indra refuses. Later, as the grounders are about to leave Camp Jaha, Octavia picks a fight with one of the grounders so she can get trained with them like she wanted to. The grounder (Fio) beats her up pretty severely, but Octavia continues to stand up again and again until Indra calls it off. As Octavia is recuperating from the fight, Indra appears and tells her that she fought like a child but Indra is willing to train her and take her on as her Second. Octavia agrees. After Indra and the grounders bring back food for the people of Camp Jaha, Kane acknowledges that it was Octavia who brought the Grounders and the Sky People together. Fio, the man she had sparred with earlier, brings her a plate of food. Kane asks her to "look out for [her] people," to which Octavia ambiguously replies that she is.
In Coup de Grâce, Octavia and Indra work together to take down two Mountain Men scouts who attempt to kill Clarke. Indra instructs the other Grounder to stand back and let Octavia fight the remaining scout. Octavia successfully takes him down and brings him back to Camp Jaha for questioning. Later both Octavia and Indra go with Clarke and few other Grounders as they get Emerson out of his cell and order him to send a message to Mount Weather.
In Rubicon, Octavia is seen in Tondc with Indra telling her that she is worried about Lincoln not being back yet. Indra answers that Lincoln is no longer her concern and that she can worry about him when the battle is finished.
In Resurrection, after the bombing at Tondc, Lincoln saves Indra from the rubble just before Indra is shot in the chest by the sniper who coordinated the bombing. Lincoln decides to go after the shooter, telling Octavia that she needs to remain with Nyko and help him since Indra was shot by the sniper. Indra tells Octavia that because she's the Chief's Second, she must make the other Seconds follow her. The other Seconds tell Octavia that they can't do anything until Lincoln takes out the sniper. Octavia comes up with a plan to block the sniper's line-of-sight so they can get to the wreckage where Abby and Kane are trapped and the other Seconds follow her and they start to dig out the survivors. She is overjoyed to see Lincoln return alive after taking out the shooter and looks on with pride when Indra finally welcomes Lincoln back into their clan.
In Bodyguard of Lies, After Octavia figures out that Clarke and Lexa knew about the bombing in Tondc ahead of time, Lexa sends Octavia off to keep watch. Clarke sees Indra and asks why she isn't keeping watch with Octavia. Indra says that Octavia is off scouting with Lincoln, making Clarke realize that Lexa was planning to assassinate Octavia and saves Octavia's life, unbeknownst to her. Later, Clarke tells Octavia she wants to take her out of the mines and put her in the rear guard so she won't get hurt but Octavia says no, stating she only listens to Indra and then ends their friendship by telling Clarke she only fights this war with her because she wants their friends back. She and Indra discuss the Tondc bombing and she doesn't understand why Indra isn't mad at Lexa and Clarke for letting all those Grounders die. Indra tells her it was the Mountain Men who were responsible for their deaths.
In Blood Must Have Blood (Part 1), Octavia travels into the mines with Indra, Jackson, several Grounders, and several Sky People to clear the mines of Reapers so Bellamy can get the delinquents and the imprisoned grounders safely out of Mount Weather. Later, Octavia thanks Indra for forgiving Lincoln. Octavia uses Lincoln's maps of the mines to find the way to the Mount Weather intake door. They eventually reach the door to Mount Weather and Indra tells her she's a Grounder now, much to Octavia's pleasure. They soon they hear the horn sounding retreat and Indra orders Octavia to leave the mines with them, but Octavia tells her she is not leaving without her brother. Indra tells her she is no longer her Second and symbolically cuts her. After Indra and the Grounders leave, Jackson asks Octavia to come home with the Sky People. Octavia tells him she has no home and Jackson leaves with the others while Octavia stays in the mines.
In Blood Must Have Blood (Part 2), Lincoln has been apprehended and is tied to a tree. Indra walks up to him and places a knife beside him, telling him Octavia has already made her choice and now he has to choose whether to stay here or march on to Mount Weather, but if he does he will be breaking the Grounder alliance with the Mountain Men. Lincoln takes the knife and heads toward Mount Weather and Octavia.