Is there any way Harry can save his Great-grandfather? Will Harry be placed in Gryffindor or Slytherin? While he will be welcomed and have a better chance at making friends easily if in Gryffindor. In Slytherin he might be able to destroy Voldemort's recruiting grounds from the inside. And be a leader and help with overcoming the house rivalries. And help protect the Slytherins who don’t want to follow Voldemort but might get gained up on.