There are six mares - seven, more recently, and a dragon - that make up a very small group that, despite its best efforts, manages to save Equestria. Of this group, no two mares aggravate each other more than Rarity and Rainbow Dash.
To one, the other is snooty, uptight, boring, and girly, and to the other, the one is Rainbow Dash; an adjective here used to mean 'Annoying, pushy, arrogant, stubborn, and too cute for her own good.'
Together, they manage to aggravate themselves into love, and although they might seem like a pair of bickering mares to outsiders, if you asked either one if they really loved the other, their answer would be 'definitely.'

A series of short one-or-two shots focused around my ship du jour a la horse. Rated T for now, but there may be some smut later on.

Art by the lovely Servidor; go check it out.