These are the Doctor and Twilight from Doctor Whooves Adventures, after their encounter with the parallel Doctor and Derpy from Doctor Whooves and Assistant. This Doctor met Twilight first and made her his Companion. The other Doctor met Derpy first and made her his Assistant (classical). If you want to see those two reunited, this artist did another pic: cleppyclep.deviantart.com/art/… with DWaA Doctor and Derpy. Check it.