If Sherlock gives John a jumper, he'll probably ask if it's for a case.
When Sherlock says it isn't, John will give him a suspicious look.
He'll ask whether Sherlock has 'accidentally' destroyed one of his other jumpers.
When Sherlock says he hasn't, John will feel confused.
He'll joke that November is a bit early to be giving out Christmas presents.
When Sherlock says it has nothing to do with the holidays, John will feel more confused.
He'll hold up the jumper and examine it closely, admiring its softness.
Then he'll notice the way Sherlock is looking at him, and he'll feel even more confused.
He'll ask Sherlock why he's giving him this jumper.
When Sherlock says that he knew it would bring out the color of John's eyes, John will feel so confused that he'll forget to breathe.
He'll have to sit down on the sofa.
Then Sherlock will kneel down in front of him and take the jumper out of his hands.
John will gasp as Sherlock slips his fingers under the hem of the old beige jumper he's been wearing all day.
But he'll raise his arms helpfully to allow Sherlock to pull the old jumper off.
And he'll keep his arms up to allow Sherlock to put the new jumper on.
Then he'll need to put his arms down.
So, he'll wrap them around Sherlock.
And chances are, once John wraps his arms around Sherlock, one thing will lead to another, and that new jumper will soon be coming back off.
...
End Notes: Chances are, if you leave me a review, I'll write you some more fluff. :)