Mischief and His Twins

Lily Potter nee Evans wasn't a muggle-born at all. She came from a line of squibs who also had creature blood in them. When Harry was born he inherited that creature gene and is now a Cheshire cat. He is also Dumbledore's grandson. He also finds out that he has two mates who know how to prank and swear. How will this change Harry's first year.