The first time you called him “daddy,” it was a joke.

…Mostly.

You’d just returned from a joint mission with the 8th Division—dust on your boots, blood on your collar, a split in your sleeve you hadn’t noticed until Shunsui himself pointed it out with an almost disappointed pout.

“Tsk, tsk,” he said, tapping your arm with his fan. “You’ve gotta take better care of yourself, sweetheart. What if I wasn’t around to patch you up, hmm?”

And before you could stop yourself, before you could even think, you smirked and said:

“Well, that’s why you’re here, daddy.”

Silence.

His fan paused mid-flutter.

One of his eyebrows arched slowly, as if lifting a curtain on the part of his mind you were not ready to enter.

“…Say that again?” he asked, voice lazy, but dangerous.

You blinked.

“Oh no,” you whispered, too late.

He leaned in close—so close you could feel the warmth of sake on his breath, the curve of his smirk just shy of your cheek.

“You do realize I’m going to remember that forever now.”

The second time, it was on purpose.

He was stretching under a plum tree in the 8th Division garden, sleeves rolled, haori cast aside, hair undone from its usual lazy tie. A summer breeze blew through the courtyard, and you’d come to drop off a report. But the moment you saw him—shirt slightly rumpled, neck on display, eyes half-lidded—you just couldn’t help it.

“Hard at work, huh, daddy?” you said, deadpan.

Shunsui dropped the sake bottle in his hand.

Not because he was surprised.

Because he was laughing too hard.

By the fifth time, it had become a thing.

“Careful, daddy.”

“Whatever you say, daddy.”

“Don’t forget your hat, daddy.”

Each time, he reacted differently.

A wink. A groan. A teasing flick of his fan against your cheek. And once—just once—a low murmur of “If you keep saying that, I might start to believe you mean it.”

You did.

You absolutely did.

But you weren’t telling him that.

Yet.

One afternoon, after a long sparring session, you flopped onto the polished wood floor of the dojo, panting. Shunsui stood over you, not even winded, one hand on his hip, the other tipping his straw hat back.

“I’ve gotta admit,” he said, “you’ve gotten stronger. I might have to start trying.”