Prompt 17: Living Together

So this prompt came to mind after reading 'Nemesis' by ShinichiKudo on 'fanfiktion . de':

Conan is back to being Shinichi and can finally live alone in the Kudo Mansion again.
But his joy doesn't last longer than a few weeks. Suddenly his parents come home and decide to stay for several days. Even worse is that the day they leave, out of the blue he gets the notice that the son of Yukiko's deceased disguise teacher is going to live with him for a few months in the Kudo Mansion (because of some reason).
The moment he lays eyes on the other teen, he instantly recognizes him as KID – but being introduced as Kuroba Kaito. Kaito too is less than pleased, having guessed that his cover would be blown right away by his favorite critic and hoped that Shinichi would at least not tell anyone.

With their mindset of "He's a thief/detective – my fiend – only a grudging ally in extreme situations!" they constantly annoy each other and fight. Both of them too prideful to admit that they don't actually hate each other and unfortunately that anger also blinds them from noticing each other's feelings. And that's how their time living under one roof starts!

I had this scene in my head, where they fight and part angrily and when Kaito (or Shinichi) leaves to go to his room, the other looks after them sadly, realizing that they screwed up again.
This story is post-BO and post-Conan, Kaito also knows Conan is Shinichi.
When they start living together, they aren't in love yet, but already like each other, even if neither of them wants to admit to it. That's why this story could even start out as ShinRan and KaiAo, as long as it ends with KaiShin or ShinKai.