AN:Set post Volume 15.
The first time they kiss is on an otherwise unremarkable evening. The two of them are outside eating dinner when, very matter-of-factly, Doumeki leans over and presses his lips to Watanuki's. Watanuki, predictably, freaks out. He does not, however, try to stop Doumeki when he leans in for another kiss not ten minutes later.
The first time they have sex is a just over a week after their first kiss. Doumeki is, for the most part, silent, while Watanuki is very vocal. His usual demands that Doumeki "kneel and worship at the feet of the great Watanuki-sama," however, are atypically low and lustful. And, for the first time ever, Doumeki complies.
The first time they sleep together is right after the first time they have sex. Watanuki ends up sprawled out on top of Doumeki, who has his arms gently twined around the other man's waist. Watanuki's sleep-fueled murmurings are mostly nonsensical, the only coherent bit being "love… Yuuko." Doumeki takes a deep breath in before relaxing the grip that had automatically tightened in response to Watanuki's words. This is not, admittedly, everything Doumeki wants, but it is more than enough to go on with the business of being happy.