Ok, I know, it sounds ridiculous. Just hear me out. What if Itsuki had a crush on Kyon, and he didn't want to just be friends, so he acted annoying on purpose so Kyon wouldn't try to get to know him? This idea hit me a few days ago, and I had to write it. So I might be posting that fanfic here, if I can resist putting in a lemon.
Back to the topic. Then, what if Haruhi started watching Yaoi, and got really into it, and subconsciously used her god powers or whatever to make Kyon bisexual? And then, what if Itsuki got visited by the future Kyon and Itsuki, who were dating, and was told to tell Kyon how he felt? And then what if the future Itsuki and Kyon went back in time again the same day Little Itsuki was telling Little Kyon how he felt to make sure he gave Little Itsuki a chance? Please, if you write fanfiction and like this pairing, USE this plot device, just make sure to vary it a little so people don't think we did it on purpose lol.