Vapor Trail

Depiction in the series
Vapor Trail is a female pegasus pony seen in the season 6 episode, Top Bolt. She is very close friends to Sky Stinger and loves spending time with him supporting his dream to become a Wonderbolt.

It is later discovered that throughout the time she has spent with him, she has also been helping him fly professionally to get into the academy. She never told Sky this because she didn't wan't to crush his hopes, but when Twilight and Rainbow Dash convinced her this was the only way to solve their friendship problem, she eventually confessed to him.

Finally, (with a bit of training from Twilight and Rainbow Dash), the two pegasi's talents were seen and they were both accepted into the academy.