Sherlock watched John. He liked to watch John.
Of course, you could argue that Sherlock Holmes watched everybody and everything, but, when he watched John, it was different somehow.
He didn't just watch so he could deduce, he watched him because he liked to.
This realisation confused Sherlock. He enjoyed watching John? Why?
He decided to examine a typical morning - well, as typical a morning as Sherlock and John ever have! - to see if he could figure it out.
Morning saw John awake and arise early. Sherlock didn't care much for routines or clock-watching but, as John was up, Sherlock got up too. He entered the living room to find John making tea and toast in the kitchen.
Sherlock threw himself on the sofa, facing the kitchen so he could watch discreetly. He smiled as John glided effortlessly from cupboard to kettle to fridge to counter to toaster, like a routine choreographed with military precision.
"Breakfast?" John called out, without losing his rhythm one bit.
Sherlock, being Sherlock, didn't answer, of course, but John slid two extra slices into the toaster and laid out two tea cups anyway.
Breakfast was passed in a companionable silence, only occasionally broken by the rustle of paper as John read the morning news - Mrs Hudson always ensures that the morning paper is there for them early in the morning. She's good like that - and the putting-down of tea cups.
Sherlock used this time - time when John is occupied; distracted but close - to watch. He watched John's face as it reacted to the news he read. He watched the way John closed his eyes as he savoured that first cup of tea of the day. He watched John's legs as they crossed in front of him, supporting the newspaper with a practised ease. Legs of a soldier: tight; strong; no longer in need of a cane.
The image of John using a cane crushed Sherlock momentarily. How broken John was then. The outside world saw John the soldier; John the doctor; John invalided home but still strong, alive, upright. Shoulders back, chest out, face resolute.
The world saw, but it did not observe.
The world didn't not observe the John that was being destroyed deep down inside. The John who screamed silently at the cane and gazed longingly at the pistol.
Sherlock had seen that John. Sherlock had rescued that John.
He took a deep, grounding breath.
"Bored already?" John asked, raising an eyebrow as he glanced across the top of the paper. He'd mistaken the long exhalation for a sigh. Understandable, Sherlock supposed. He decided to play along.
Sherlock motioned his hand waywardly towards the general direction of his phone. "Nothing from Lestrade yet." he started, trying to feign a boredom that he wasn't actually feeling, "Anything in the papers?"
John didn't answer him, but he folded up the paper and laid it on his lap, watching the detective closely. Studying him? Giving him his undivided attention.
Sherlock frowned. "What?" he finally asked when the scrutiny had lasted just longer than was comfortable from this side of the study.
"You ok?" John enquired, mirroring Sherlock's frown. "You seem... distracted." John followed up with a slightly crazed laugh. "More distracted than your usual self, I mean."
Sherlock just shrugged and smiled. He didn't really have an answer. He was distracted. He was distracted watching John Watson. Observing every twitch. Every nuance. The way his face crinkled each time he smiled; each time he frowned.
Sherlock wasn't just aware of every reaction that John had though. He was also all too aware of the reaction he himself had to John. Like John could control how Sherlock felt inside without even knowing it.
John's absence made Sherlock feel empty. His presence in the room made Sherlock feel complete.
When John frowned, it made Sherlock sad inside, but when he smiled, it made Sherlock feel light as air.
And when John smiled directly at Sherlock, like he was doing right now; one of those genuine "you are crazy but you are my crazy friend" smiles, Sherlock's heart felt as though it would burst right out of chest and dance around the room - quite possibly singing something ridiculous.
It was at that precise moment that Sherlock realised what it was; what it all meant.
And a moment later, he realised just how completely screwed he was.