Tell her about your fantasies, call her Xyl

"Honestly, Xyl, I've liked the idea of being an Arachne's slave for a couple of years now. I once visited an Arachne village with a trade delegation, and after seeing the slaves, the idea of being stuffed full of eggs and ordered around gave me wet dreams for months. I suspected that it probably wouldn't be as fun to live as it would be to fantasise, but I have yet to find anything to complain about."

She blinks, looking at you with a slightly confused look on her face. "You are actually happy to be my slave?"

"I'm certainly not unhappy, Xyl."

"And yet you accepted my offer to use my name? Surely if you wanted to experience a slave's life, you would have refused."

"It clearly made you uncomfortable when I called you Mistress," you reply. "A good slave doesn't make their owner uncomfortable every time they open their mouth. Your mother said you want me to like you, but I want you to like me as well."

She looks deeply touched by that sentiment, even if she is still a bit confused.