Twilight before the Night

Title thanks to

We hath not been intimate in some thousand years, Twilight Sparkle. You seem to have us at a disadvantage."
Twilight craned her neck, closing the distance between their muzzles until only a breaths distance lay between them. "I haven't really done this before, pr-Luna." She confided with a growing blush before her tongue bridged the gap and caressed the Lunar mares nose. "But i'm an avid learner."

What is this? This..Twilight and Luna wha?! Twi you cheater! Kidding as this is actually my second favorite pairing