Celestia feels like Butterscotch is too humble for his own good, despite all the times he and the rest of the main 6 saved Equestria from the brink of disaster, so she personally invites him to her palace to give him a little reward for his many valors.

https://www.fimfiction.net/group/214700/dirty-little-secrets-dirty-little-contest

Kinks include: Rule 63 Fluttershy, 69, worshipping, vaginal sex, royal horny princess, penetration, massive creampie and impregnation