Original Vector by Chrzanek97 

So Rumble learned his lesson that ponies aren’t limited by their cutie marks. Just because a cutie mark represents something about them (whether by personality, interest, talent, what they are good at, etc.) does NOT mean they have to stick with what they do for the rest of their life. However, Mud Briar did NOT learn his lesson. 

So yeah Rumble is a sweet, innocent, outgoing colt who first started out as shy when he was introduced in the series in Season 2 along with his brother Thunderlane, and his foalsitters/sister figures Cloudchaser and Flitter. But he is now a sassy, stubborn, teenage-voiced colt but is still a cute colt nevertheless.