Tell her about your fantasies, call her Mistress

"Honestly, Mistress, 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, Mistress."

"And you intend to continue calling me Mistress as a part of that, I take it?"

"Yes, Mistress."

"I see."

She looks no less confused as you continue your journey.