There's something special about seeing the person who just vivisected you while you were perfectly conscious up until death. Although his body is tense, it's not actually that much of a change from the way he normally carries himself, has adapted to since he came to this place.

The whole place has him on the defensive constantly. As a result, his expression doesn't even flicker with Ken's approach.

He has nothing to say himself. But after a short pause, he reaches out and places a gentle hand on Ken's head.

He doesn't blame him. He had, quite literally, asked for it.