katsuki likes having his hands on you at all times. it's so mindless it just feels wrong if you're in the same room and he's not touching you?
he'll pass by you and a big hand will slide around your waist, lingering at the small of your back for no reason at all while he reaches for something above or beside you.
he doesn't even do it to fluster you, it just feels natural.
it actually took him a little while to be comfortable enough to initiate casual touches when you first started dating. his heart was pounding the first time he reached for your hand, he even accidentally gave it a quick squeeze out of nervousness. but once he felt confident enough, it was impossible to get his hands off you.
when he takes a seat next to you, his hand immediately finds your thigh, patting it a couple times fondly before resting, squeezing playfully here and there. he'll often slide your leg on top of his lap, aiming for both, as the hour goes by.
when you get up, he lets his hand trail down your leg, letting it linger while he looks up at you, the quiet timbre of his voice flustering you when he asks "where you going?" even when you're in public, it makes you want to crawl in his lap and stay there, which he would love, but there's a time and a place.
when he's passing by you as you're sitting on the couch, he'll pat you on the head, often after giving it a kiss, especially when you're busy working on something.
you never asked him to do any of this, but now it's the norm, and it feels just right.