Once upon a time, Darren Criss helped write A Very Potter Musical, a fan-made musical version of the blockbuster books that played at the University of Michigan in 2009. After the video surged on YouTube, Glee came calling, and the rest is history … until this past month, when Criss flew into Chicago to rekindle the old magic at LeakyCon 2012, a convention for Harry Potter super-fans.