He used to be a unicorn and went to celestias school for gifted unicorns because celestia saw a lot of potential and greatness within Blue Thunder.

His dad, Lightning Storm used to be one of the greatest heroes and royal guards of all equestria.

He became an alicorn when he wandered into a mysterious cave within the everfree forest searching for adventure, a mysterious stone, turning Blue Storm into an Alicorn!

”Woah! What the—?! I—I’m an… Alicorn now?!”