It had started during one of Sherlock’s “bored” phases. The first day had been Sherlock moping, the second destructive (though John had prudently taken his gun to work), the third sprawled out on the floor with his head under the couch, and the fourth observing the degree of susceptibility to hypnosis of flies. When John had come home to find everything perishable out on the counter and Sherlock naked in the refrigerator, calculating the rate at which someone lost energy through prolonged exposure, he decided he had had enough.
“Sherlock,” he began dangerously, surveying the food arrayed on all available flat surfaces around assorted science equipment, “we need to get you a hobby.”
“I don’t need a hobby,” Sherlock snapped testily back from his cramped position in the fridge. “I need a case.”
“Yes, that’s what you always say.” John started to sort through the food. “Get out of there, would you? I’m not sure what’s still usable but I’ll need to put it back.”
“The milk and eggs are still fine, the ambient temperature is cold enough to preserve them for a time.” Sulkily, the detective disentangled himself and stretched out in the tiny kitchen.
John, catching the movement, looked over involuntarily— “And go put some clothes on!”—before resolutely turning his back and repeating, “we need to get you a hobby. You can’t keep going mad every time you’re not working on something.”
“Experiments are something. Experiments are my hobby, I don’t need another one.”
“Not when they don’t preoccupy you enough, they’re not.” John deliberated over whether or not the leftover shrimp chow mein was still edible.
Sherlock swept grandly back into the room wearing pajama pants and his bathrobe. “They occupy me enough,” he said with a haughty stare.
“You know what? You’re going to learn how to bake.”
The detective’s eyes narrowed and he glared at his erstwhile companion. “I will not.”
“Yes, you will,” John replied firmly. “Put on your coat, let’s go to the store. We’ll get you some supplies.”
It took a bit more convincing than that—another hour of steadily more illogical arguments, culminating in Sherlock nearly shooting John and John whacking him with an umbrella—before they finally set out for the supermarket, Sherlock complaining every step of the way.
He complained every step of the way through John picking a recipe for cookies and figuring out what was needed to make it and the entire baking process from mixing the ingredients to taking them out of the oven. He didn’t complain about the cookies, but he did complain about John complaining about the mess Sherlock had made.
John threw up his hands in exasperation and retired for the night, leaving Sherlock grumbling in the kitchen.
But when he got up to grab a bit of breakfast in the morning, there was a large chocolate cake on the table. Sherlock was gone, and Mrs. Hudson, when asked, could only say that he’d dashed out around seven, arguing with himself over the effects of salted butter in coffee cake.
When John got home from his work at the surgery, there was another large frosted cake on the table next to the chocolate one, both with sizable slices missing, a tray of fresh onion and chive scones, another couple dozen cookies, and a loaf of bread. Sherlock was asleep on the couch, covered in flour.
Two caseless days later, there were five cakes, two soufflés, nearly two hundred cookies of various flavors, twenty half-eaten loaves of bread, a dozen varieties of scones, some half-hearted attempts at biscuits, and three pies overflowing the flat. John ended up packing most of the uneaten food up and taking it to the police station, where he dumped it all on Lestrade and quietly begged him to come up with a case for Sherlock to solve.