He doesn't speak while stripping away her clothes, to ask permission or otherwise.
When Carissa is naked and bound to the bed at four points, he snuggles up to her. Speaking feels strangely hard, he wishes he could leave the wordless mood and do everything by telepathy.
"I've asked Subirachs for magical assistance in hurting you more, despite apparently not being ready to do or even hear about any of the less magical ways of doing that," Keltham says. "She'll drop off what she can find from her collection in a few minutes, along with directions. I - feel a desire to do that to you, maybe even a need, after feeling scared about losing you."
"If you want to try to convince me about anything related to that, you have temporary permission to say what you want, including things I might potentially interpret as you objecting in words, up until the moment I first hurt you."