Geralt met John a couple of times, so I think it's about time he meets Claire. He has a daughter and thought he lost his kid twice. It's a whole thing, she keeps disappearing.

I think he'd like Claire a lot, she'd remind him of a couple of healers he knew from home, and he responds well to that kind of Soothing Energy since Geralt himself is pretty chill. He's also big on nature, living off the land, etc. He's a forest (now desert) man and knows his plants, so they can at the very least talk about trees or something.