At the end of season four, everyone had been split up in order to survive primefiyah. Now that everyone is back together again, or at least all on earth and above ground, the fissures created by a six year divide are no longer deniable. Even Bellamy is forced to admit that Octavia is no longer his sister. Yes, the Blake siblings have had their issues over the years but with Octavia becoming so powerful, even Bellamy is not safe from her wrath, nor does he seem to have much influence over her any longer. There was a time when you couldn't slide a piece of paper between these two but that time is long gone. Octavia has undeniably become a ruthless dictator under the guise of keeping her people together and safe.
For much of The 100, Clarke has acted on behalf of Skaikru, making the hard decisions in order to save as many lives as possible. Skaikru is long gone now and all that she has left is Madi. Madi as we have come to see in the passing years has become family to Clarke and her top priority. For her part, Madi has completely lost herself in all of the stories that Clarke had told her about her people and is so naive, that she doesn't really understand that these stories no longer reflect who these people are today. Octavia is so much more than the girl under the floor, she's someone to be feared now. It all comes to a head when Niylah discovers that Maddie is a nightblood. Niylah and Clarke may have history but Octavia has made it clear in the intervening years that one is either Wonkru or Nokru. Niylah's allegiances lie with Octavia and she promises that if Clarke comes clean that Octavia will show mercy. After witnessing Octavia's brutality first hand, mercy is not something Clarke trusts as something Octavia is capable of anymore.
It becomes clear just how closely Maddie has been listening to Clarke when she decides that rather than fleeing and returning to the Valley for the sake of her safety, she reveals her true identity to Octavia. Maddie is clearly way out of her element and is acting with hopeful naïveté. Maddie confesses because she knows it's not safe for Clarke in the valley. This is actually something that Clarke would have done on behalf of Skaikru in the past. For her part, Octavia identifies with Maddie because she too was forced to hide and so she makes her part of Wonkru. At this point, I can see how Octavia identifies the similarities between herself and Maddie but I don't know that it will be strong enough to save Maddie from the actual threat that she represents to Octavia's rule. Sure people are loyal but many are only loyal because of fear and lack of options, not because they believe in Octavia.
Bellamy does his best to argue for Echo's safety but Octavia is having none of it. Octavia orders Echo banished but does agree that if Echo turns in people who are unloyal that she will be allowed to stay. Sure enough, as Echo begins to pack her bags, members of Wonkru show up and ask to travel with her. They are sick of Octavia's heavy handed leadership and would rather take their risks with the outside world than live another day with Wonkru. Proving how much Echo has changed, she refuses to turn these people over to Octavia to save her own life and instead offers to infiltrate the Valley as a defector and shut down their eye in the sky. Octavia agrees to this plan but warns Echo that if she gets caught that no one is coming to save her.
Echo leads a few defectors away from Wonkru, taking Diyoza's offer to take in any of Wonkru who choose to come and live in the Valley. For Diyoza's part, it makes sense to take in people because they are going to need farmers and tech people in order to make a life in the Valley workable. Echo makes her bid for freedom but Octavia does not keep up her end of the bargain and has Miller shoot at the members of Wonkru who are trying to escape, much to Bellamy and Clarke's horror. Echo helps a young woman along and when she gets shot, she slips the chip she needs to take down the eye in the sky in the wound. Bellamy is shocked that Octavia would go as far as to kill her own people but it seems that by leaving -- as far as Octavia is concerned -- they were no longer a part of Wonkru. Octavia also tries to justify her actions by saying that this makes Echo's escape more plausible because Diyoza would never have believed that she would have just let people go. At this point, it's clear that Octavia is just used to explaining away the evil that she does in the name of Wonkru.