Bruce was not being affectionate. Bruce was giving Clark a massage, for entirely selfish reasons.

He rolled up and straddled Clark's hips with his knees, sat up and was able to use both hands, now, and that was likely going to make him much more effective at digging his fingers into muscles, stroking over cloth covered skin and just touching.

"You can be a cat who killed bunnies and are wearing their corpses as slippers. Sharks would just eat the cat."