Anything I'd add wouldn't be very informative! In most of my fandoms there is only one pairing that interests me, and it's the main characters - everyone else is secondary, even ephemeral (for instance, I love Captain Dobey in Starsky & Hutch, but don't really have any interest in writing about him). I can see other pairings and accept them, but they don't interest me enough to write about them. HP is the only fandom where my OTP is not only not obvious, it's actively horrible to a lot of people (even though it's grown vastly more popular over the years). I can't explain how it happened other than to say that what each character has in common is that he is very interesting and appealing to me. :-)