This challenge is different from my first three. This crossover challenge takes in the world of harry potter.
-The great families are powerful and ancient wizard families spread across the world and their castles like Winterfell and Highgarden are schools run by the families.
-The story should start when Harry about to go back to school in book 5.
-After the Harry's trial Dumbledore calls a meeting of the great families to tell them that Voldemort is back and gathering his followers for his new war.
-During the meeting Harry meets the families and some of the heads of them. Some of them believe Voldemort is back and join but doesn't do it for free. They want something that will benefit them.
-One of the families demand a marriage contract with their oldest daughter. After the contract is agreed upon. His betrothed goes to Hogwarts with Harry to get to know each other before they get married. Change the age of the daughter to be near Harry age. Like make Myrcella older or Arianne younger.
-I would like to see something happen after the HP books that Harry has to battle against. Voldermort was just a prelude to whats to come like the White Walkers or some other evil.