But Why?
It's a wonder, John thinks, that Sherlock's not collapsed yet. 48 hours, he's counting, 52 minutes. Soon it will be too much.
"But why?" Sherlock asks, his voice raw. It's the 57th time he's asked. John has yet to answer. (He will, afterwards.) "I trusted -," Sherlock closes his mouth under John's stare and they continue the competition of staring at each other.
"56 hours is my limit," John says. "Or was. I don't know anymore." He knows that by that time he will not be thinking as straight as he still is but he doesn't matter. And he wonders how he'll find out limits if his is shorter than Sherlock's.
Sherlock's hands are tied behind him. He's sitting on a chair John led him to when he began the experiment. (It's Sherlock's own fault. John needs to know these things and he knew Sherlock would go with it if he coated it with the word experiment. There's something in that word that makes Sherlock always melt.)
Sometimes John sees Sherlock struggling against sleep. He wants to – needs to show John. Needs to get away and fight John (who knows he might win given the chance. So he isn't).
"I could make you feel better," John says, 9th time. They both know what he means and Sherlock still insists he wants nothing of the sort. That being tied to a chair would kill all of that. (It doesn't, they know it, both, but John let's Sherlock insist if he wants to).
Sherlock says nothing and John stares. It's a permission, if anything.
"Are you sure?"
The annoyance is clear in Sherlock's voice. "I've been tied to this damned chair for the last 24 hours – well, except for the short moments you've taken me to the bathroom – with only you as company. Being fed. Just. Are you even going to tell me why?"
"I said it the first time. After," John answers and wonders why Sherlock never really objected. How much they trust each other even when the other seems to act as a lunatic or a killer or something.
Sherlock huffs and John knows he's just annoyed that he won't tell him. That he can't read it in John. So he doesn't say anything, just walks to Sherlock, staring down at him (it's weird, being taller, having power over the other man).
"Will you deny kissing?" John asks because he needs to know even if he could just do as he pleases and Sherlock would quite likely let him. He let himself be tied, anyway.
Sherlock looks right into his eyes with that piercing stare (it's not cold, it's never cold when it's at John because) and John leans down to capture his captive's lips. Sherlock bites, just to let him know that this isn't the time to be tender and from there it's easy to pretend that this is all a game (and it is, isn't it) and soon John is opening the jeans Sherlock is wearing.
John doesn't tease like he normally would. He wonders if this will affect his test, make Sherlock drowsy and fall asleep earlier than he really would.
"Stop thinking. It won't, I'm pretty sure that this ridiculous experiment would have ended sooner rather than later anyway."
John kind of hates it when Sherlock seems to read his mind. He glares at Sherlock who just raises his eyebrows. They let it pass and John continues, he finds Sherlock's cock in his mouth soon and it's all so familiar (but Sherlock's just sitting, he can't really move and John knows he hates it, hates it so much and it gives him the thrills) and he gives the best he can.
It doesn't take long and John wonders, out loud: "How long were you hard? Because it normally takes much longer."
And this time the stare is colder but it doesn't work when otherwise Sherlock looks so sated. He doesn't answer and there are no noises around them.
John is still counting (49 hours and 54 minutes) and he keeps on looking at Sherlock. Wanting to explain. Not knowing what he really can say. Sherlock doesn't ask anymore, it seems he's accepted he won't get the answer before later (or he's trying to figure everything out in his mind). John doesn't ask for help with his own erection. He lets it be, he doesn't need the satisfaction right now.
50 hours and 34 minutes is when Sherlock falls asleep. John lets him free from the chair and carries and half drags him to his bed, wondering what he'll be up to the next day.
"Why?"
John opens his eyes and notices his hands are tied to the bed. He doesn't panic. He kind of had an idea of this happening.
"I needed it. I needed to know," he answers. "So I'll know whilst you're on cases. And how much it takes to break you."
Sherlock smiles and John swallows. They trust each other but sometimes it's hard to remember, why. "I have an experiment I'd like to try."
John doesn't deny anything from Sherlock. Especially when he's tied to his bed.