It's always the quiet ones... While studying ways to make a super solider to protect Equestra from evil Fluttershy was hit with a massive amount of gamma rays. At first there were no apparent side effects until something pushed her just a bit too far. Fluttershy's anger suddenly manifested itself and she became as Rainbow Dash described it a green angry rage monster... with purple pants, that nearly destroyed ponyville. Luckily it is hard to break her constant calm.