ninjago hc i've had for years: kai's fire powers naturally increase his body temp, meaning he makes a very good heating pad.
nya will come flop over his lap with her face in the couch cushions while he's playing video games or something and he'll just pretend she's not there while he smashes through a level.
or lloyd (who runs cold due to being part dragon) will crawl into bed with him during the winter because he's cold and kai doesn't mind.
and then post-ice emperor zane, having all his joints fucked up from 60 years of constant below freezing temperatures (and kinda not moving from that one spot for all that time so they're all super locked up) will kinda drape over kai's back sometimes when they're standing.
like the corruption also made him partly organic so he can 1000% feel pain and EVERYTHING hurts for the first few years after coming home and he is super not used to it. leaning on kai somehow makes zane hurt less so it's become a lot more common to see him do it
masters of fire are living heating pads and you can't convince me otherwise