So I'm really into the idea of Arthur getting friendly (flirty or no) with a vampire who is trying to be not awful. He is a smart guy but somewhat blinded by other people's good intentions and/or their pretty faces, and even though he's technically a vampire hunter he doesn't have the emotional baggage/trauma that seems to run deep with the rest of Hillingdon, so I'd be down for them meeting in a context where he knows she's a vampire or one where he finds out further down the line! When I started typing this comment I really didn't have a direction in mind, but even as networking contacts I think they'd work pretty well together.

Also he is half-decent at flirting.