This was a patreon reward Smudge_proof way back in October of 2017, based on the episode Marks and Recreation, which had come out recently at the time.
 
The CMC’s efforts have paid off and they’ve helped Rumble in getting his Cutie mark. Unfortunately for them, it seems his talent is in hypnotizing others. Applebloom and Scootaloo are now slaves to his every desire, obeying his every order.
 
Rumble decides to enjoy his new playthings while he waits for Sweetie Belle to come back with more fillies for him to hypnotize. Soon he’ll have a harem of girls debasing themselves and worshiping his cock.

imported from https://derpibooru.org/images/1810463