Sounds pretty hilarious actually, having a nearly immortal hostile companion following you around gnawing on your leg
on one of the endings i did for platinum (I think it was BoS) I went in and was murdering everyone in the institute, and instead of following the quest markers i went into the room where X-88 hangs out, since i was killing everyone in the institute he was of course hostile, thing is he was still flagged as essential and thus couldn't be killed. so he starts attacking me, i put him down and everyone else in the room, leave the room and he stands up and follows me out. stats shooting me again. I turn and put him down again, he gets up and keeps doing it.
I had to reload and stay away from the room because the immortal assassin synth chasing me