The first time it happened, Iida convinced himself it had been borne of necessity. He'd come home from work one chilly fall evening to find his boyfriend curled up on the couch, wearing one of Iida's own sweatshirts with a blanket draped across his legs. "Katsuki," he said, surprised and a little amused, "you can turn on the heat, you know."
"I'm fine," Katsuki insisted. Iida just smiled and adjusted the temperature himself without saying another word. He did not ask why Katsuki had been wearing his sweatshirt; perhaps his own winter clothes were still in storage for the season.
The next time was a few weeks later - a morning so cold it was difficult to get out of bed. Iida lingered as long as he dared, but eventually necessity forced him out of his cocoon of blankets. At the kitchen table, his hands wrapped tightly around a mug of coffee, sat Katsuki - wearing what was unquestionably one of Iida's sweaters. It was one of his favorites, too, a thick knitted dark blue one with intricate cabling of which he was particularly fond. While it fit Iida, it was far too large for Katsuki; the broadness of the garment's chest and shoulders made him look small by comparison.
"You're wearing my shirt," Iida remarked.
Katsuki lifted his gaze slowly and nodded. Then he took another sip of coffee. Iida waited for some kind of reaction - an explanation, perhaps, or an apology, or a belated You don't mind, do you? - but there was nothing. Katsuki's expression seemed simply to say No shit.
"Why are you wearing my shirt?" Iida tried again.
"It looked warm."
"Do you not have enough warm clothes? I know you don't typically purchase sweaters for yourself, but you've got plenty of sweatshirts, haven't you?" He saw them every time he looked in the closet - they were constantly engaging his own clothing in territorial disputes. "If you want more sweaters, though, I can go shopping."
Katsuki gave him another long, inscrutable look, then turned his attention to his breakfast.
Iida let it go. When Katsuki was in this sort of a mood, there was simply nothing to be done.
Iida went to the store he typically bought his own sweaters at and purchased several for Katsuki. And Katsuki did wear them, as different as they were from his usual style. Iida felt happy to have made good choices - they fit flatteringly, and the colors he'd chosen, black and dark brown and wine-red, looked good against his pale skin tone, bringing out the color in his eyes.
But one day, when work was slow, Iida came home early and found Katsuki lounging in bed, wearing one of Iida's sweaters once again. It was the same sweater as the previous time, the dark blue one. Iida paused in the bedroom doorway and stared, and Katsuki stared back at him, defiant and challenging but not saying a word.
"Katsuki," Iida said, padding over, "I don't understand why you continue to wear my sweaters."
"You got a problem with it?" Katsuki growled. He wasn't wearing pants, Iida noticed, just sitting bare-legged in bed with the sweater draped over his frame, loose and long. That didn't make any sense, either: if he was warm enough to have his legs bare, why was he wearing a sweater at all?
Iida continued gazing at him. Katsuki in turn seemed to be fascinated with his phone, his cheeks turning pink under Iida's gaze.
Then something clicked in Iida's mind. Perhaps it wasn't about warmth at all; perhaps it wasn't about having his own sweaters available. More likely it was something entirely unrelated that had compelled Katsuki to slip one of Iida's on while he'd believed Iida to be away for the afternoon.
He sat on the bed beside Katsuki and leaned down to kiss his collarbone, which was visible thanks to the sweater's too-loose collar. Iida kissed his way up Katsuki's neck and jaw to his ear, and, smiling, he whispered, "I have no problem with it at all."
"Well, good," Katsuki said. Iida kissed him on the mouth, holding him in his arms and feeling Katsuki's hands pulling him closer, gripping tightly onto the material of his shirt. Yes, Iida thought happily, I would be a fool to have a problem with this.