In Harry Potter and the Deathly Hallows the entire house of Slytherin sits out the Battle of Hogwarts. In the book, it’s because they all evacuate through a secret passage, like refugees. This is voluntary, as a portion of each of the other houses do stay to fight. Or it could be interpreted that McGonagall evicted them. In the movie, she explicitly orders them all to the dungeon because they’re all a bunch of untrustworthy gits. Who’s to say one of them won’t abracadabra you in the back because he wants to be in Voldemort’s good graces? They all want that awkward hug A lot of readers/viewers say this was…