Opposites; c.h + m.c [c.s]

"You're not sexually attracted to people and I'm sexually attracted to everyone, you're dark and I'm pale, you play bass and I play guitar; it's like some one said 'fuck it, opposites attract so let's make these fall in love!' And that's how it happened"

or

the one where Calum is asexual and Michael is pansexual and they fall in love because after all, opposites attract.