He can't even remember what the fight was about.
He remembers how it ended – him spitting the words you heartless shit at Sherlock like venom, Sherlock gazing inscrutably back at him, the satisfyingly dense slam of the door behind him.
He does remember what it was about, of course, if he's honest with himself and stops pacing the length of his tiny hotel room for long enough to really think.
The victim had been hospitalized with end-stage liver disease. A chronic alcoholic, he'd been in and out of the ward with complications resulting from cirrhosis for years and years, had tried repeatedly to get sober without success. Textbook, Sherlock had said dismissively, and even that had prickled at John.
His doctors were only able to administer the mildest of painkillers, because anything else would tank his already failing liver. As a result, he was dying in agony.
His sister had taken it upon herself to administer the strong stuff herself, in a lethal dose. She'd arrived in their living room seemingly not to seek answers so much as to confess, and to establish whether anything could be proved against her.
Sherlock had been blunt and brutish as ever with her, interrupting her at the very worst possible moments, and John should be used to it but this is different, this is too close.
"It never ceases to amaze," Sherlock had remarked, afterwards. "The human capacity for self-delusion. She knew for years he was killing himself, acted only when she had the least appealing set of options remaining. Bizarre."
He'd said it absently, his attention on his laptop, the case already semi-forgotten and it struck John, again, just how little everything meant to him.
"You really don't have a fucking clue, do you?" John had said, words half-broken by a humourless chuckle.
He hadn't mentioned Harry by name, but God knows Sherlock has never needed any help before with figuring him out. It shouldn't come as a surprise any longer, Sherlock's capacity for thoughtless brutality, but he knows John and he knows the terror he has suffered – her cycles of newfound resolve and inevitable decline, her slurred voicemails, her poorly disguised edema – and he hadn't cared enough to keep his mouth shut.
John scuffed his shoe into the carpet irritably. What the hell was he doing here? He'd gone straight to Paddington and caught a train to Bristol, with the half-baked intention of going to see Harry, but realised too late that he'd left his phone at Baker Street. He doesn't even have her most recent address.
Good, he had thought viciously as he slammed through the platform barriers, imagining his phone buzzing uselessly on the table as Sherlock texted him. Let his bloody demands fall on deaf ears for once.
So here he is, waking up at a Travelodge. In Bristol. For absolutely no conceivable reason besides Sherlock being a knob and his own remarkable ability to continue being surprised by his knobbishness.
In the cold light of morning, though, his anger's beginning to recede. For all that Sherlock could be intentionally cruel, in this instance he'd been doing nothing of the sort. It was pure ignorance, a borderline autistic moment of insensitivity that was nothing out of the ordinary, and with some fourteen hours now between himself and the argument John can't avoid the feeling that he'd overreacted.
Nor the feeling that it's ridiculous to be spending money on a hotel room in the hometown he has no desire to revisit. The large digital clock on the bedside table is mocking him, counting down every minute he's wasting on this stupid jaunt during which Sherlock probably won't even notice he's gone.
At 9:08, he makes a cup of tea.
At 9:34 he takes the Bible out, has a flick through, thinks better of it.
At 10:17, he goes for a walk, taking in deep gulps of the morning air, trying to clear his mind.
He manages to while away most of the day walking the streets with no specific destination in mind, stewing, his anger feeling less and less rooted by the second. Nonetheless, he is very, very determined not to go home before at least 24 hours have gone by, as though this arbitrary measure of time will be the thing that really shakes Sherlock to his core.
Finally, after he's exhausted all of the city's major parks and drunk about as many solo cups of coffee as he can stand, he admits defeat and boards a train back to London.
The flat is dark when he finally gets back. He thinks of calling for Sherlock, but stops himself, overwhelmed by the faintly immature feeling that he isn't the one who should have to make the first move, though God knows it'll end up being him anyway.
As he's reaching for his phone, it leaps into action, and as he goes to answer he notices that his missed calls are in double figures.
"Hello?"
"Where the hell have you been?"
Lestrade.
"I've, err—I was away overnight, forgot to take my phone. Why?"
There's a pause, Lestrade taking what sounds like a deep breath, and cold settles abruptly into John's stomach.
"Sherlock?" he asks, voice suddenly uneven.
"He's okay. There was a situation, early this morning. Ten hostages, a gunman we're pretty positive was working for Moriarty. He was feeding Sherlock riddles and letting the hostages go if he solved them in time. Sherlock was in there too. He saved eleven of them, but the last one was killed."
"And?"
"It was Mycroft."
"What was?"
"The last hostage was Mycroft."