*shrugs* I'm really not sure... they work well together, they click at a whole lot of points, I guess. It's actually a sort of lazy appeal (for me) in that respect, because it makes them easier to write. I've got another pairing I'm trying to get going, and it's so damn difficult to get the guys together that I've been working on the story for, like, a year now with nothign posted yet because they're obstinate. Not so AoSou... they just gel. That's probably how it goes for me.