"I've seen enough men turn tail at the idea of being father to their own children," she says with a roll of her eyes.

Nina's quiet for a moment, staring off at some space between them. "Now and then his age would come up. He was nearing or just over a hundred, you know. Sometimes I think caring for someone like me was a little frightening. I'll live a long life, thanks to being what I am, but even I'd be looking old at a hundred. I'd die eventually."

She knows, from Geralt, that witchers are hardly immortal, but their changes their bodies go through make them terribly long-lived. Centuries of life, provided they aren't killed in the course of their work.