John figured it out a few months after moving in to Sherlock’s room. At first he didn’t notice anything odd, at least anything odd compared to what he was expecting to find. A few discarded wrappers, nothing out of the ordinary. It wasn’t until he dropped a pair of pants under the bed one morning that he discovered it.
“Sherlock?” John called, slightly puzzled. Sherlock popped his head around the door, a questioning look on his face.
“What’s wrong? Did you find the experiment?” John shook his head then looked up, alarmed.
“No, I-wait what? An experiment? Really Sherlock, we talked about this, no experiments in our room! Anyway, that’s not what I’m talking about. What’s with all these boxes of candy under the bed?” Sherlock frowned and stepped into the room, walking over to where John sat on the bed. John fixed him with a look and Sherlock squirmed.
“You weren’t supposed to find those. I had hoped you wouldn’t notice.” John huffed and shook his head again.
“Sherlock, I live in this room now. How was I not going to notice? I would’ve eventually.” Sherlock nodded and looked down. John visibly softened and reached out a hand to coax Sherlock’s chin back up. “Hey now don’t be upset, I was just curious. You don’t have to tell me if you don’t want to.” Sherlock nodded again and smiled.
“It’s nothing I’d get upset over; I just don’t want to really explain it. It’s a long story, I’m not sure you want to hear it.” John smiled as well and just looked at him expectantly. Sherlock rolled his eyes before continuing. “Alright John, but only because it’s you and I trust you won’t tell anyone. When I was a child, I loved sweets. Mycroft and my parents wouldn’t let me have them, as they thought it was unbefitting for a child like myself. Mycroft wasn’t allowed to have any either, but I still think it’s because he was too fat. Whenever I had any, I would stash it so it wouldn’t get taken from me. This became normal and I still do it, the only difference is that I eat it all the time because I still believe it will be taken.” John smiled and reached up to kiss him, stepping into the circle of his arms.
“Thank you for sharing that with me, love, I really appreciate it.” John reached to kiss him again but stopped and blinked, then a knowing expression spread over his face. “Wait, is this how you go for so long without eating?” Sherlock nodded and smirked.
“Good deductive skills, Doctor Watson. Yes, it is, and I’m still going to continue to do it.” John just shook his head and mock-glared at the detective.
“Sherlock, I really wish you would eat more. Wait a second! That’s why when we kiss it tastes like candy! I always wondered about that.” John and Sherlock burst into giggles and leaned into each other, struggling to breathe. John leaned over and kissed him once more, smiling at the ever-present taste of candy. “How much of this stuff do you eat? It’s not even nine in the morning!” Sherlock just shrugged and kissed John again.