I love working through the stages of grief that Rhonda mentioned. Also, making sure he is mentally working toward something.

But even if they are physically treating him fine, that doesn't mean someone isn't lying to him. He would probably kill for news of the outside world, and what if one of the characters -minor or major- becomes the antagonist here by feeding them the wrong things.

Suddenly he could be trying to figure out what is real and what is not as well as trying to get away and do what he needs to do. Make it all muddled. Having him mentally sort through what must be true with what couldn't be true would be a new torture.

Good luck!!!