If he did this to a normal dath ilani woman she'd be at least saying 'ow' and the fact that Carissa isn't - yelling, isn't having her face tighten up in pain, that she can still choose to just smile at him in response - he feels like he needs to hurt her more than this, take that control away from her, and he almost stops to ask if he's thinking it right, except that he, he can see himself as others see him, he can see his own story as a reader would see it, he can guess where this is going and if not Carissa can tell him in words to stop -
His other hand seizes her nipple, traps it between thumbnail and forefinger-nail, and bites down with those fingers as much as his grip strength allows.