Harry Potter and the Beast of Slytherin

Harry Potter uses the Basilisk to defeat Tom Riddle's diary, forcing Dumbledore to realize that Harry is more powerful than he realized. Dumbledore will then need to reevaluate his plans. Harry grows up through his teen years with the beast at his side, until they finally meet Voldemort once more. Fate will bring these two together, but who and what will fight to keep them apart?