"Sherlock, I trust you."

That was all Sherlock ever needed to hear. Of course, he would never admit that to John. Obviously.

It was truly nice to be trusted by someone again- if not for the first time. Did Mycroft trust him? Hardly. Mrs. Hudson was just his landlady, she didn't count. Molly? Infatuation does not go hand in hand with loyalty. And although Molly was loyal, after pushing her away for so much time, even she had begun to recoil. And he was only needed by Lestrade out of necessity.

However, John was always by his side. Ready to run with him, sacrifice after sacrifice. Who else would go flat-seeking with him after only meeting the day before? Surely, living with him couldn't have been easy. And John never complained- at least not literally. However, fraudulent quips of their living arrangements hardly fazed Sherlock. In fact, he found them amusing.

There was that one moment where Sherlock slipped, however. Not necessarily slipped, for it was out of necessity that he had to expose his own feelings for a brief moment.

"I don't have friends; I've just got one."

And it was true. He couldn't lose John, if even for a moment. Although no one knew, he craved their friendship, the companionship. Not only John's company, but the trust and bond between one another. John Watson had become his own adventure, and he loved their time spent together. He didn't want to lose that for a second. This was the truth. He had to say anything- the truth, even- to keep John in that moment. And the truth was said only, albeit not fully, because although he was not the world's only consulting detective, John Watson was Sherlock's friend, his only friend, and he knew when a lie escaped his lips.

John would never know, though. He couldn't. Sherlock would never tell John what he meant to him, not when it wasn't necessary anyhow. And certainly not in full, excruciating detail. Not with all the suffering John would go through when he would be on his own.

Is it egotistical to say John would suffer? Maybe John wouldn't suffer without him. But, basing solely off Sherlock's inevitable own reaction, he can only make a logical deduction that John would equally react. Sherlock wanted to leave as little pain in his wake as possible. And if leaving John ignorant of Sherlock's own love of their friendship would soften John's suffering, Sherlock would do everything in his power to keep his thoughts to himself.

Leaving John wouldn't be easy, not in the slightest. Not being fond of sentiment, he shouldn't be considering John's reaction in the first place. But Sherlock had long ago accepted that John was the one person for whom he could, and must, feel.

Sherlock took into account his friend John's feelings and ultimately decided that when it was time to leave John, he would leave him with no knowledge of Sherlock's own tremendous loss. The loss of his only friend. Sherlock constantly reminded himself of his own adage: that sentiment is a chemical defect found in the losing side. But Sherlock did not apply this to himself. He only thought of John Watson, because he did not want his friend to be on the losing side.