[Oh, yeah, he absolutely spots that change, his horrible grin curving up even wider -]

- You...! You even went so far as to change the color of your blood...! It's - no, you!
You're beautiful!
Breathtaking, spectacular...!

[Which he is, of course, going to also show through his actions - one hand reaching down to grab at her thigh so he can hold her still, immediately going for a rhythm that's as fast as he pleases.
She did say he could let loose, after all, so he's going to!]