César, being César, can't stop himself from immediately trying to look for said skeleton wolf when he hears the claws. Despite the conversation. He hesitates and looks back to River, confessing quietly:

"She's not hunting me. I'd be dead repeatedly if she was. But if I run into her, she might kill me out of convenience."

He's not going to say what the trauma is, belatedly processing that River will give him that boundary. César's grateful.

"I've been walking around afraid my life could end at any second when I'm away from crowds. ... and there's relatively few people here."