"John, why didn't you bring a coat?" Sherlock demanded. It was nearly freezing outside, and John was walking about wearing only a jumper.
"If you recall, Sherlock, you rather rushed us out of there. I didn't have time to grab it from the closet," John explained as he kept pace. They were hurrying to a crime scene, and true, Sherlock had rushed them a bit, there wasn't even time to hail a cab. They'd have to walk. But with John exposed like this he'd fall ill before they even reached the scene. Sherlock stopped and John came to a halt a few steps later, walking back to ask why Sherlock wasn't walking. Before he had the chance, Sherlock peeled off his overcoat and helped John into it- well, forced John into it. John protested the whole while.
"But Sherlock, you've only got on your shirt underneath, you'll freeze," John insisted, trying to remove the coat when Sherlock started walking again.
"No, I won't, but if you take that coat off I won't wear it and we'll both be ill and you'll just have to put up with it," Sherlock threatened. He'd nearly forced his scarf on the doctor as well, but wisely assumed that the line would be drawn there. Besides, Sherlock wasn't all that cold, seeing John in his clothing warmed him up considerably. When they arrived at the crime scene, Lestrade somehow managed to keep a straight face, an impressive feat considering how the coat swam on John's smaller frame.
"Oi, Freak! Boyfriend forget his coat?" Sally called mockingly. John turned on her smoothly and walked over. Sherlock couldn't hear what he said, but considering Sally's expression, it must've been quite good. John came back over a moment later, and linked hands calmly with Sherlock.
"What did you say?" Sherlock asked under his breath while they examined the body. Nothing too interesting, a crime of passion, former boyfriend reappeared at an inopportune time, presumably while current boyfriend was present. The woman had sent her boyfriend away so she could deal with her ex, and had wound up dead in the alley. Simple.
"I told her that just because she was frozen through and through didn't mean I had to be," John said softly. Sherlock chuckled, and John sent him a gently reproachful look. Ah, that's right, laughing over bodies was a bit not good. Sherlock straightened up and gave Lestrade the rundown before tugging John away from the crime scene.
"We're hailing a cab this time," John insisted, stepping to the curb when Sherlock began to walk back towards the flat. Sherlock began to protest, but John all but shoved him into the cab. He quickly settled in next to the detective, nestling neatly into his side. "I'm not having you catch ill just because I forgot my coat," John murmured.
Sherlock smiled, pulling his doctor closer to him. He'd never be cold so long as John was around.