Former Ravenclaw, same year as Harry. Member of the DA, he went back to school to finish his NEWTs properly. He's a Potionmaker and works for Draco Malfoy.
During his 7th Year (the first one), he was tortured and badly injured by the Carrows. He also was injured in his attempt to buy Harry some time to find the diadem and due to both these events, Michael remains with a slight limp and a stutter when stressed out or unable to really take his time to speak.
He is as calm as possible at all times, exactly because he doesn't like this to be common knowledge.