I finally got over myself and wrote a BirthRate fanfiction~ It's based on an ImagineYourOTP prompt, which I've quoted at the end of the story. Enjoy!
On the joy of locked doors
Hell would freeze over at least four times and Nice would be elected President of the United States twice before Ratio understood why he and Birthday always found the strangest pretexts for making out. Today, the event leading up to their current situation had been a meaningless argument about something stupid - neither could actually remember what it was now. The important part was that they had wound up speaking with so much sexual subtext that Koneko had covered Hajime's ears, scolding them for "being inappropriate for any audience". Birthday had shrugged the matter off in that unconcerned way he always did.
"It's not my fault if they attach extra meaning to the things I say, is it, Ratio-chan?" he had laughed when Ratio had told him that they should probably take their banter elsewhere. "But if you insist on finding someplace more private..." Wiggling his eyebrows suggestively, he had grabbed his partner by the wrist and dragged him off upstairs. Once they got to the spare guest room, Birthday had shoved the door out of the way and headed inside eagerly, Ratio still in tow. The doctor had known right away what would follow. Sure enough, moments later, the door was closed and they were up against the wall, making out.
Presently, Ratio drags a gloved hand through his boyfriend's short blond hair slowly, in exactly the way he knows Birthday likes, eliciting a groan from him. Grinning into the kiss, Birthday responds by slipping his arms around Ratio's neck and pressing their bodies very close together. Their tongues slide across each other repeatedly. Birthday soon decides he's had enough of just kissing. He pulls away, reluctantly breaking the passionate lip-lock, and fixes Ratio with a seductive smirk.
"You know what? Something's bothering me," declares the blond.
"Oh? And what might that be?" Ratio asks, knowing full well what the answer is.
"Your clothes. They're on you and they really shouldn't be." As he says this, Birthday trails his hands down and slips Ratio's white jacket off his shoulders, letting it fall to the floor carelessly.
"Hmm. Why don't you help me fix that little problem then?" Voice laced with implication, Ratio returns Birthday's confident grin with an equally suggestive (though perhaps less confident) one. A small laugh escapes his boyfriend's lips. He hums his agreement as he reverses their positions, now flattening Ratio's back to the wall with the pressure of his own body as he loosens Ratio's tie. The soft skin of his boyfriend's neck then proceeds to distract him from his goal of taking Ratio's clothes off.
"Hey, isn't there some law against someone's neck looking so damn appetizing?" asks Birthday jokingly. Before Ratio can reply, Birthday's already giving him a hickey. Ratio sighs, reveling in the pleasant and yet unusual feeling. One of his hands twines its way into Birthday's hair yet again, tugging lightly in a manner which he knows is entirely enjoyable.
It ends too soon for Ratio's taste. Luckily, however, Birthday quickly returns to his original goal of getting his boyfriend out of his clothes. Looking up and meeting the other's one visible blue eye, Birthday makes a right show of popping open each individual button of Ratio's shirt, gradually exposing the skin beneath. The strange thought suddenly occurs to Ratio that Birthday's not wearing sunglasses; he assumes they must have fallen off sometime before Birthday gave him that hickey. He discards the thought as Birthday straightens up and shrugs his own jacket off, tossing it to the side. He then pulls his shirt over his head and flings it off in a random direction without looking to see where it'll land. Grin widening, Birthday tugs at the sleeves of Ratio's shirt until it's entirely in his hands before it, too, is thrown away over the blond's shoulders.
Ratio is still pressed back against the wall, kissing Birthday hard, when the latter decides that pants are also unnecessary. His hand trails down Ratio's toned chest until it comes to a stop on his belt. Birthday kisses back with just a little extra effort as he starts to fumble with the belt when the door abruptly opens.
"... don't know what they'd be doing in a guest room anyway." The pair only catch the second half of Murasaki's sentence.
"Each other, probably," replies Nice offhandedly. He probably means it as a joke, but then again, it is Nice – it could well be that he knows.
Birthday and Ratio barely have the chance to share a look of shock before Hamatora's other duo spots them.
"... Oh." Nice doesn't have a sassy remark at hand, just a simple "oh," which means he probably hadn't meant his earlier suggestion seriously. Murasaki coughs when the awkward moment stretches on a little too long.
"Um, we'll let the client know you guys are busy," says Nice before heading back out onto the landing. They receive one "really?"-look from Murasaki before he follows Nice back downstairs.
The moment the door clicks shut behind them, Ratio fixes Birthday with an incredulous look.
"You didn't lock the door?" he asks, sounding more exasperated than angry (probably because he is more exasperated than angry).
"Erm, no?" tries Birthday, grinning sheepishly. "Aw come on Ratio, neither did you."
Ratio rolls his eyes. He's smiling against his will.
"How about we finish this in my bedroom?" he suggests, and it takes less than five minutes for the two of them to grab the clothes they had thrown around and rush into Ratio's room, this time remembering to lock the door.
Well if that wasn't suggestive~ Anyway, the idea for this fic came from the following prompt: "Imagine your OTP kissing in a private area with the door unlocked, and person A begins to undress person A, and one of their mutual friends walks through the unlocked door". Thank you for reading, please leave a review (no flames though!) :)