Heartwarming: The Return of Princess Nightmare Moon
Nightmare Moon and Bandaid's time together in part 2 of A Carnival, Bandaid! in the sequel is very loving and heartfelt. Especially when you remember that Nightmare Moon is usually loud and boisterous and Bandaid is very uncomfortable with mares.
Faust's interaction with both Celestia and Chrysalis in the chapter Faust Almighty, Bandaid! in the sequel is very heartwarming.