Claire thinks she's a strong person for having the guts to do what she thinks is right/just/necessary, even if she isn't as powerful as the people she'd be going up against. Moral courage in the face of adversity is a big respect-winner for Claire. And uh yeah he sees killing off goons in a spate of revenge murders as moral courage, just to be clear. And her toughness despite her sweet appearance is pretty... idk, endearing to him? You're a cool dame, Nill. Claire normally works alone and would see other people trying to get in on his murders as a burden rather than a help, but he feels like he can't really refuse under the circumstances. He'd probably give her a bit of a hard time at first just to check she's really got what it takes to go through with it, but in the end he respects her determination too much to outright refuse and he'd rather be working alongside her than have her be a rogue agent.

He also likes her just as a person who's around the boarding house. She can get flustered over him trying to drive a tank over the lawn and be chill the next time they meet; she's quite easy-going for all her fire, and he appreciates that and gets energy from her positivity. She's the type of person he'd like to go to for gossiping about relationships, whether she wanted to put up with that or not! He'd also want to try and push her and Chane together more because aside from their common living area and mute-ness he thinks Nill would be the kind of friend Chane needs... she's optimistic and determined just like him, hahahah.