Not related to Luna Bagel, but its still good!
BANANA PIE BACK-STORY:
Well that’s a long one. He never met his parents because he was raised in an orphanage (not a traumatically bad one though). When he was old enough to leave, he left Trottingham and made his way to Ponyville, where he started working in the banana shop he currently owns. However, he was still a blank-flank until he offended Celestia, and she sent him to the moon. While on the moon, he found a huuuuuuuuuuuuge pile of bananas (one can only imagine how they got there)! Out of the fruit, moon rock, and a few other materials he found there, he cleverly made a rocket ship that allowed him head to home back in Equestria!