Your Accuser, Your Companion
Everybody on Binary Five is guilty, in the eyes of the Wardens. They want to make sure that guilt is in your eyes too.
One of your victims lives in your head. If you were a murderer, they worked up the template from recordings and testimony; if you were a rapist, they probably got the victim to model it. If you were a terrorist, they could have done either. None of the inmates are sure if it's done with hypnosis, implants, broadcasts--who knows? What matters is that the person who brought you to trial never leaves your sight and hearing.
Some Companions will try to teach you guilt, reminding you every hour of how helpless they were, how sickening your actions. Some mock you, pointing out the shame of what you endure and do now to keep going. Some say nothing: they just stand there, in corners and on ledges, and bleed.
If you ever want to accomplish something on your own on Binary Five, you'll have to defeat your Companion one way or another. It's not as easy as it sounds.