A Harry Potter Fan Fic wherein Harry Potter snaps at his trial for underage magic in Order of the Phoenix, and becomes a greater darkness than Voldemort himself. Can be found here.
First, Harry begins murdering his enemies, including Malfoy, Snape and Umbridge. Dumbledore's Army forms as in canon, but Harry uses it as a nucleus and training program for the Black Tide, the army with which he intends to conquer the world, while he styles himself the Dark Jester. Ron and Hermione eventually realize something is wrong and flee with a portion of the group, becoming Harry's primary rivals, the White Shore. Harry then kills Dumbledore, razes Hogwarts to the the ground, and builds his citadel, the Jester's Keep over the ruins.
After that, it's all endless battles and atrocities in a four-way war between the Tide, the Shore, the Ministry and the Death Eaters.
Harry's Madness contains examples of:
- And I Must Scream: Dudley Dursley has his head sewn on to a Frankenstein's monster, Grawp with some parts from dragons and a manticore added and is used as a weapon for months.
- The Bad Guy Wins: To the point where the story trailed off (over a decade prior to this posting) the Black Tide enjoyed an almost unbroken string of victories.
- Black Magic: Necromancy at least exists in this story, Harry tutors Ginny in it and she eventually outstrips him.
- Black Sheep: Ginny alone of the Weasleys joins Harry and becomes his chief necromancer, using her father's skull. Seamus also disdains his family and devises a way for his parents to witness all his atrocities.
- The Corrupter: Harry turns Ginny, Neville and Seamus into depraved monsters who would each probably be the Big Bad in another story.
- Crapsack World: Dumbledore is dead, thousands of innocent people too, the masquerade is rent asunder and the evil Black Tide and the increasingly militaristic and xenophobic Ministry square off to decide who will rule the world, with only the tiny White Shore as unambiguous good guys.
- Deal with the Devil: Ginny presents her father's skull to a demon, in exchange for lessons in Necromancy.
- Despair Event Horizon: For Harry, it's being left alone at his expulsion hearing.
- Eldritch Abomination: Early on, Harry is able to kill several opponents, including Albus Dumbledore, simply by removing his Jester's Mask and letting them see his true form. This isn't followed up on later, and may well be an example of Early-Installment Weirdness.
- Evil Minions: The Black Tide as a whole are Harry's minions. Divided into a few subcategories.
- Marauders are the basic infantry, equipped with black plate armor, face-concealing helmet, and short swords in place of wands, better for sweeping and area of effect spells.
- Dusk Knights are the Marauder cavalry, riding giant spiders.
- Purgers are Marauders armed with magical flamethrowers and orange, dragon-themed versions of the Marauder armor in fire-resistant dragon-hide.
- Necromancers, and attendant undead minions.
- Elementalists who wield powerful element-themed magic.
- Marauders are the basic infantry, equipped with black plate armor, face-concealing helmet, and short swords in place of wands, better for sweeping and area of effect spells.
- Eye Scream: Seamus has his parents chained to a wall and plucks one eye from each, keeping them in a glass sphere on a necklace, so they can see every horrible thing he does.
- Fallen Hero: Harry Potter, implicit in the premise.
- Field of Blades: One battle becomes known as "The Forest of Spears" for precisely this reason.
- From Nobody to Nightmare: Harry Potter can hardly count as a nobody at any point. His inner council, however...
- Seamus Finnegan, the Dark General, is Harry's military commander, and author of many of the Tide's atrocities. He also takes to wearing his parent's eyes in a necklace, so they can see what he's become.
- Ginny Weasley murders her own father for necromantic power, and raises legions of the dead.
- Neville Longbottom is in charge of the Elemental wizards, and steals the power of the Water Orb, and thus supreme power over water, for himself.
- Giant Spider: The Black Tide kill Aragog and raise many of his children to become their spider cavalry.
- Horse of a Different Color: The Black Tide's Dusk Knights ride Acromantulas into battle.
- Monster Clown: Harry seems to straddle the line between a Scary Clown and an Eldritch Horror.
- Murder Is the Best Solution: Before going public, Harry murders Umbridge, Snape, Malfoy, Shacklebolt, Fudge, and Arthur Weasley, not to mention Albus Dumbledore.
- Necromancy: The Tide employs thousands of Necromancers, under the leadership of Ginny.
- The Plague: Utilized against Hogsmeade by the Tide's Necromancers.
- Playing with Fire: The Purgers, a special corps of Black Tide troops who utilize magical flamethrowers and fire-resistant dragon-hide armor. Also Fire Elementalists.
- Villain Protagonist: The story follows the Black Tide, with only a few interludes giving insight into the other factions.
