2016 alicorn anal atryl blue_eyes blue_fur closed_eyes clothed clothing collaboration comic cunnilingus dialogue english_text equine female feral friendship_is_magic fur group hair hi_res hooves horn inside mammal multicolored_hair my_little_pony oral penetration princess_celestia_(mlp) princess_luna_(mlp) purple_fur rimming sex sibling siden sisters text tongue tongue_out twilight_sparkle_(mlp) underhoof vaginal_penetration white_fur wings yuri