[Nepeta doesn't notice right away. She's too busy reading and of course that random page happens to land on...one of the more explicit parts and jesus christ. Her own face is turning a rather lovely shade of red as well and she closes the book looking down at him.

The makes her smile return and she shuffles the top of his head before getting off]

Aw. I'm sorry, Karkat. I only wanted to see what it was---I didn't mean to upset you. But it's no big deal if you like this kind of stuff.