Firestorm was your usual unicorn, except that he ran the biggest fireworks company in the whole of Equestria.
Chasing Haze was a pegasus with more to him than most would expect, and he preferred it that way.
One makes fireworks, the other works for Fire Services, and both need to find what they never knew they were missing.

But sometimes the past doesn't stay behind you. Poor Ponyville will never know what hit it.