You were always kind to him, even though he rarely spoke. He appreciated your defense against Shinobu's rude remarks.

He never had someone like you who wasn't rude about his quiet nature or emo appearance. Despite being the Water Hashira, people don't treat him as such,

The only people who were nice to him were Mitsuri, Rengoku, Tanjiro, and others. He likes you a lot so he tries to ever so slightly get glances at you at Hashira meetings and goes out of his way to try to talk with you.