"Mrs. Hudson, we aren't decorating for Christmas," John reminded their landlady one Christmas Eve.
"I know, but I'm just giving the place a little color," Mrs. Hudson replied absentmindedly as she arraigned some greenery over the fireplace.
Since Sherlock and John didn't plan on having any company that holiday season, they had decided to just skip the events entirely, including the decorating the flat. Of course, Mrs. Hudson had protested, and snuck in small Christmas-y items when she thought John and Sherlock weren't looking. As the holiday drew closer, she soon gave up any attempt at decorating secretly and started doing it in plain sight. To her enjoyment, the boys didn't mind that much.
"Still, don't go overboard," John said, leaning against the doorway to the kitchen, just as Sherlock walked in the front door.
"Back so soon?" Mrs. Hudson asked.
"The case wasn't that challenging. It was obvious the killer was the brother," Sherlock answered.
"That's nice," Mrs. Hudson turned back to the fireplace, sneaking a small glance out of the corner of her eye. Just as she planned, Sherlock moved to go to the kitchen.
He barely stepped through the entrance when Mrs. Hudson cleared her throat loudly, catching the attention of both her tenants. At their questioning looks, she pointed above them.
Mistletoe.
John and Sherlock exchanged an awkward glance (more awkward on John's part, as per usual Sherlock didn't show his emotions).
"I'll give you a little privacy," Mrs. Hudson said with a smirk, and exited the flat.
Neither John nor Sherlock moved.
"Um, we don't have to, that is, if you don't-" John stammered out.
"Tradition, John," Sherlock quickly interrupted.
"Okay-"
John was cut off again as Sherlock swiftly pressed his lips against John's, the light kiss quickly deepening, both men giving into what they've wanted to do for so long. They only parted when they ran out of air, but they still kept their foreheads pressed together.
A light smile spread across Sherlock's face.
"Merry Christmas, John."
A/N: It always was my headcannon that Mrs. Hudson shipped Johnlock and in subtle ways tried to get them together. I'm not to please with how the kissing bit came out, but oh well...