Revan, of course, has treated player characters very cruelly on many occasions, but he never seemed to take control of them.
Well, I don't control them anymore, but they technically still exist in the world. Converting a character to an NPC when the player abandons them sounds quite logical. Okay, resurrecting Keliandra is a bit much, especially since you can only summon creepy creatures there, but Vortex would look quite good among the other Rinzei.