As a devoted fan of some fandoms (e.g., Harry Potter, Percy Jackson, Avengers), I like to read fanfiction of them. There are many of them out there, but there are a few, like this one which are diamonds in the rough. Oh God, Not Again! is a Harry Potter fanfiction written by Sarah1281 which tells the tale of Harry Potter who slipped through the Veil in the Department of Mysteries and is sent back in time to his 11th birthday. On TV Tropes, this is considered to be one of the lighter Peggy Sue fics out there, where the story is not as serious, as Harry does not purposely set out to save everyone that had died in the Second Wizarding War.
The Harry in this fanfic is very, very, out of character. He doesn’t mope around and his personality’s only used to make the plot even more incredulous with him doing things like claiming that his scar is psychic and exploiting his future knowledge of Basilisk attacks in his second year to make a mint off of selling mirrors and books on the beast alongside Mandrake Restoratives. As a road less travelled, Lockhart is not portrayed as a complete dunderhead and actually manages to get on Harry’s good side as the professor reveals his cunning, scheming side.
Of course, with the pre-knowledge of the latter half of the books, Harry manipulates the events leading up to Order of the Phoenix such that post-Triwizard Tournament plot points never happened. This means Umbridge never gets her comeuppance, which is something that most readers (myself included) love reading.
I highly recommend this fanfic if you’re looking for a lengthy story that satirises Harry’s awesomeness. If you really enjoy it, you may also like another fic of the author’s titled Run that be me again? which goes over some plot points where some characters don’t exercise any common sense.