Tomura doesn't allow other people to get close to him, never allowing strange touches or odd bouts of intimacy from anyone he would even think of considering as a friend or ally. It's not due to some noble reason of never wanting to hurt a living being with his quirk, but for the sake of hating vermin entering his personal space.
This is different, though. Call him a hypocrite if you'd like, he wouldn't really mind it, but being with you simply felt different. He isn't opposed to letting you invade his bubble nor allowing you to grab at him like a child in a toy store.
Dare he say it's almost cute.
"You're going to prune if you don't get out soon," Tomura rasps, his head still hanging back, his long wisps of hair nearly touching the tile of your bathroom floor. The steam feels nice on his aching body, aching skin, his eyes held closed as if it took more effort to keep them open.
The sentence almost feels ironic considering his entire body already looks like a dehydrated sack of plums, yet he digresses. You don't have the same excuse, you shouldn't let your body look like that on purpose. Even if he would regret letting you get out of the bath so soon.
He's like a child in that sense, always wanting to cling to your side while never letting you get too far out of his reach. If you left then he would leave too. If you wanted to bathe then he would bathe too, it's why he's in here in the first place.
"We could use more hot water," he continues absentmindedly, a gloved finger trailing down the length of your spine just to watch you shiver in response.