DrT is not a great fan of where Rowling left us after the sixth book. That might be an explanation for this startling one chapter story. It tells the end of the story. Harry fought through the seventh year as hidden „third forth“. On a planing meeting of the Death Eaters on the ministry he kills everyone but Snape. Then he follows Snape to Dumbledores hideaway, who was not yet killed after all. Harry explains that Dumbledore played on destroying Voldemort by destroying Harry. Harry kills him, sends Snape one to Voldemort who kills him. Then Harry follows again and kills Voldemort.
There was a surprising Death Eater Harry did not kill because she showed regret: Hannah.
The Story can be read at The Dark Arts.
There is also a PDF.