The red queen says that Octavia already died but I think that Octavia is still inside of her, she just doesn't show it. I can tell that in the last episode she was struggling to make the right decision. I could tell that she didn't want to put her Brother or Indra in that arena but she couldn't be known as weak, so she did it anyways. She set the algae farm on fire just so they'd have to march to the valley.