A.N.: Okay, so the prompt for this one was "The First Emotion of Love", which I am maybe stretching juuuust a little bit. But I had to get one of my actual OTPs in here somewhere.
A Little Bit Unconventional
Taichi can't remember when he fell in love with Koushiro. It's a little embarrassing, really, especially since it's a question people always seem to want to ask once they know he fell for a childhood friend. And it always seems to happen the same way, too. Every time the subject of relationships comes up—and it does so with almost depressing regularity—there it is. Sandwiched in somewhere between the "That's so sweet" comment (he's pretty sure that there's nothing especially "sweet" about the way he carelessly, almost accidentally stumbled into a relationship after years of just being friends who were more than usually close) and the rather more annoying question about what their partners think about it all (which just goes to show that people really dig deep sometimes to try and find drama, and usually has him saying something like: "That it's great, because there's someone else to pester for food?").
He's gotten used to it, of course, and always deflects the "when" question with the same smile and shrug, and off-hand comment about how it was just this gradual thing, you know? No big deal, not a major issue, and certainly not something he keeps himself awake at night over sometimes, trying to pinpoint because, god dammit, this is a thing he should know.
Mostly, though, he doesn't mind. After all, Koushiro certainly doesn't, and generally he tends to think that Koushiro's opinion is the only one which actually matters. And the truth of it is, it probably did happen gradually. It seemed to creep up on him without his noticing, somewhere in the background behind the other pressing issues of his teens, normal and otherwise. It's not as though everyone else had to worry about the potential end of the world three times before reaching adulthood. Can a guy be blamed for making that his priority? Honestly, the only thing which matters is that he did work it out. Eventually.
Koushiro knows exactly when he first knew he was in love with Taichi, because it was the result of a careful decision based on all the available evidence he could find on the internet. Naturally, of course, the emotion was there some time prior to this, but the exact moment he put a name to it was when he looked up the definition of the word and reached the conclusion that, on balance, what he was experiencing was more likely to be love than anything else. However unconventional the circumstances.
The search in question took place one evening a short while after Taichi stopped looking for poor excuses to stay overnight at Koushiro's apartment, and admitted that it was because he preferred it to staying at his own. At that point, Koushiro considered it only fair to be able to put a name to his own feelings. He'd never particularly given the matter much thought before—it wasn't as though it especially changed anything about how they interacted, after all—but he preferred to know where things stood in his own mind.
In the event, it turned out to be quite a while before the information became useful, anyway. Taichi had always been a person consumed by the moment, and their lives had always been rather full of moments to distract them. Even without the digital world, Koushiro always accepted the fact that he would always share Taichi's life with soccer, and his responsibility as a big brother. Adding the digital world and Taichi's sense of duty towards it made for a rather hectic adolescence and young-adulthood. They'd technically been living together for two years before Taichi thought to move the furniture out of his mostly-abandoned apartment and terminate his contract there.
It's not until they've been living together for three years that Taichi thinks to ask why Koushiro has a seemingly unimportant date in September marked on his calendar every year. The look on Taichi's face when he tells him the answer is every bit worth the wait.