As most of you are now aware, the brother of the pony version of Fluttershy will appear in the Friendship is Magic episode "Flutter Brutter".
But what about the HUMAN version of Fluttershy? Does she have a brother too? I suspect the human version of Fluttershy's brother will make an appearance in the EG movie "Legend of Everfree".
If Fluttershy's brother is older than his sister, he probably already graduated from high school. If he is younger than his sister, or they are the same age because they are fraternal twins, here's a possible scenario: Flutterbrother was a student at Crystal Prep Academy, but was expelled from Crystal Prep thanks to bad grades or poor discipline, and winds up at Canterlot High School.