Eris is a Manchurian candidate. She didn't escape from CE. She was transformed and released by one of oryx's sisters. This is the queen she was referring to at the end of regicide. The thing most people don't pick up on is we didn't defeat oryx IN his throne room. He was hovering outside the ship. I don't believe that he is fully dead. My speculation is that his body will be found on saturn and his worm will be transferred. Eris will see to this as she serves another.