It's the year 1975 and Death Eater's are at large with raids happening more often than not, making the Order of the Phoenix and the Auror's at the Ministry running like headless chickens, running them thin.
Hogwart's isn't free from all this like most might think; Voldemort has his clutches in the students there and he doesn't care who you are, as long as you prove yourself useful then he will accept you.Whether you are from Slytherin or Gryffindor, Neutral-Dark or Fully Dark, 17 or 14, he will welcome you into the fold. But be careful, he doesn't accept betrayal and backstabbing so if you even think of something like that make sure that your will is updated because he will know what you are planning and he won't leave you alone. You will either be tortured or killed. There will be no do-overs.
Dumbledore, on the other hand, will only accept students that are seventeen years or older and who were either in Gryffindor or Hufflepuff, the two Light Houses.
Neutral students are in the middle; neither Neutral-Light or Neutral-Dark. These are the ones that want nothing to do with the war but know that sooner or later they will need to pick a side.
Whether you become a Death Eater or an Order of the Phoenix member or even an Auror, the war will catch up to you. So be prepared because not even Hogwarts is safe anymore.