John settled down at the table, shoving away some of Sherlock's experiments to make room for the large pile of blank generic Christmas cards he'd bought. They weren't really even Christmas cards, more of thank-you-for-not-murdering-my-flatmate cards. John went through them methodically, signing them and addressing them with a mindless ease that years of doing them for Harry gave him.
Sherlock swept inside, a blast of chilly air following him as he slammed the door shut with his heel and peeled off his coat and scarf. "What on earth are all those for?" Sherlock demanded. "Surely we don't know that many people."
The army doctor turned to glare at Sherlock over his shoulder. "One for Mrs. Hudson, one for Mycroft, one for Greg, one for Molly, a group one for Anderson, Donovan and the lot, and one for Harry. Six is hardly a lot of people, Sherlock," John scolded mildly. Sherlock scoffed. "Quit moaning and come sign these for me," John insisted, shoving the four that he'd already filled out over towards the mad detective.
Sherlock settled into a chair opposite John with annoyance etched on his face. He took a pen off the table and began scribbling furiously at the cards. Part of John was a little curious as to what the man was writing, but most of him just didn't want to know. If what had been written proved too offensive, he'd simply copy Sherlock's signature onto a new set of cards.
"There," John said, sliding the last card over to Sherlock to sign. "That's the lot of them. Would you get the stamps?" he added once the detective had finished signing the final card. Sherlock glared at him for a moment but rose and grabbed not only the stamps but also envelopes for the cards.
John quickly skimmed the cards, noting that Sherlock had actually been rather pleasant, scribbling a standard happy holidays above his signature. He passed them over to Sherlock, who slid them into the envelopes and sealed them with a lick across the glue. John very pointedly ignored that tongue and filled the remaining envelopes himself before rising from his seat and gathering them into a pile.
"Coming to the post office with me?" John asked. Sherlock made a grumpy noise in his throat but got up and yanked his coat on so he could follow. Halfway down the hall Sherlock reached between them and grabbed John's free hand. When the doctor looked over at him, startled, the detective rolled his eyes.
"Oh, don't pretend you didn't expect it, John." John nodded slightly, with a smile spreading over his face and they carried on to the post office, hands linked firmly between them.