''The Darkness Series'' by [[http://www.fanfiction.net/u/2328854/Athey Athey]], also found [[http://archiveofourown.org/users/Athy/pseuds/Athy here]], available on FanFiction.net and ArchiveOfOurOwn is a ''Franchise/HarryPotter'' ForWantOfANail [[AlternateUniverseFic AU]] where Harry goes to TheDarkSide and a SlashFic that ships Harry and Voldemort.

It consists of ''[[http://archiveofourown.org/works/272696/chapters/431154 Harry Potter]]'' ''and the'' ''[[http://www.fanfiction.net/s/6163339/1/Harry-Potter-and-the-Descent-into-Darkness Descent into Darkness]]'', and its sequel ''[[http://archiveofourown.org/works/272706/chapters/431191 Harry Potter]]'' ''and the'' ''[[http://www.fanfiction.net/s/6367096/27/Harry-Potter-and-the-Breeding-Darkness Breeding Darkness]]'', which was left unfinished but later adopted by two different authors: Danyealle-sama on adultfanfiction.net and Darth Keyara [[http://www.fanfiction.net/s/7744525/1/ on FanFiction.net]].

''Harry Potter and the Descent Into Darkness'' is a 4th year AU. Through an accident Harry and Voldemort's Horcrux begin to interact and Harry slowly begins to change. He becomes stronger and slowly grows aware of the sinister events that have perpetuated his entire life.

The sequel, ''Harry Potter and the Breeding Darkness'' picks up right where ''Descent Into Darkness'' left off—Harry escapes Privet Dr for the summer after 4th year by staying with Tom. His summer consists of Death Eater meetings, training, and discovering new depths to his relationship with the Dark Lord and Harry grows and changes even more.

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!!''The Darkness Series'' provides examples of:
* AboveGoodAndEvil: Harry and Voldemort.
* AirVentPassageway: Harry uses this when doing spy work at Riddle Manor [[spoiler: [[JustifiedTrope in snake form.]]]]
* AlternateUniverseFic
* AssholeVictim: [[spoiler: Rita Skeeter. Also Moaning Myrtle is RetConned into one-she was one of the girls that ruthlessly mocked Tom after he was outed while still at school.]]
* AuraVision: Ron does this with Harry in Divination class.
* AxeCrazy: Harry when playing with dark magic.
* {{Badass}}: Harry
** BadassBookworm: Harry becomes much more studious after discovering the wonders of Dark Magic. Hermione is naively thrilled with this development.
** BadassGay: Harry takes it in stride after Rita outs him to the Wizarding World.
* BecameTheirOwnAntithesis: Harry.
* BigFancyHouse: Riddle Manor and Morhda Abbey.
* BrokenAce: [[spoiler: Harry after the Tournament. Also Tom Riddle.]]
* BrutalHonesty: Harry's new favored method of dealing with his "friends" when he's not lying through his teeth.
* BunnyEarsLawyer: [[spoiler: Luna is the only one who really knows what's going on.]]
* CassandraTruth: When picking Harry's "treasure" for the Second Task of the Tri-Wizard Tournament the cup comes up blank when picking a hostage for Harry to save. Everyone assumes the cup is malfunctioning. No one considers that maybe there's no one at Hogwarts that Harry gives a damn about anymore. Also in Divination class Ron scryed that Harry is a manipulative liar and a murderer but immediately dismisses it as having misread the results.
* TheCharmer: Dark!Harry is very charming and wraps Fleur around his little finger.
* TheChessmaster: Dumbledore, Voldemort, Snape, Harry.
* TheChosenOne: [[spoiler: Voldemort was Chosen by Magic to be the Dark Lord.]] Also Harry was chosen to be the Dark Lord's equal.
* CigaretteOfAnxiety: Draco takes to smoking during his prefect rounds. Of course they're not ''muggle cigarettes.'' They're ''magic cigarettes'' that don't cause lung cancer.
* ClaspYourHandsIfYouDeceive: Harry develops this character tic.
* ClosetKey: [[spoiler: the undeniably male horcrux shade for Harry]] and Harry for Draco.
* ComingOutStory: [[spoiler: Rita outs Harry to the Wizarding World.]]
* ConsummateLiar: Harry becomes one with practice.
* CoolChair: Voldemort's got some cool wing-backed chairs at his manor.
* TheCorruption: [[spoiler: the power of the Horcrux once Harry stops fighting it.]]
* TheCorrupter: In ''Breeding Darkness'' Harry subtly plays this for Hermione and Neville and many others at Hogwarts as he helps spread the study of Dark magic.
* CruelAndUnusualDeath: [[spoiler: Harry's "experiments" on Rita.]]
* DarkFic
* DarkIsEvil: TheDarkSide corrupts Harry and he doesn't even realize how much he's changed.
* DarkIsNotEvil: Harry argues this when [[spoiler: [[TalkingTheMonsterToDeath he uses Parseltongue to talk down the dragon during the First Task]]]]. Can a non-violent solution really be so bad? Also [[spoiler: The Dark Lord was GoodAllAlong.]]
* DarkMessiah: Harry and [[spoiler: Voldemort.]]
* TheDarkSide
* TheDarkSideWillMakeYouForget
* DatingCatwoman: [[spoiler: Hermione Granger and Viktor Krum.]]
* DetectEvil: There's a spell that detects a wizard's Light or Dark alignment. There's another spell that circumvents this and gives such a test a false reading.
* TheDeterminator: {{Lampshaded}} when [[spoiler: Harry walked on a broken ankle to finish the Tournament.]]
* {{Doorstopper}}
* DoubleReverseQuadrupleAgent: Snape.
* TheDragon: Harry to Voldemort, at first. Voldemort later decides to introduce [[spoiler: Evan Harris]] as [[BigBadDuumvirate his equal.]]
* DeadFic: ''Harry Potter and the Breeding Darkness'', though it was later adopted by two different authors.
* DespairEventHorizon: Harry at the beginning of the story after his friends abandon him and he's shunned by the whole school. [[spoiler: It's what leads him letting the Horcrux out.]]
* DrunkOnTheDarkSide: Harry while he's trying out some new curses on [[spoiler: the Basilisk corpse and later on Rita Skeeter.]]
* EasilyForgiven: Subverted. When Ron and Hermione finally realize they were [[JerkAss jerks]] and try to apologize Harry pretends to accept but he isn't going to forgive them this time. He will pretend to go back to being their friend because it's easy but he swears they will never be friends again.
* EvilCostumeSwitch: After summer break Harry returns to Hogwarts with a whole new wardrobe.
* EvilFeelsGood: After [[spoiler: releasing the horcrux]] Harry immediately feels better, more powerful, more confident. This is implicit later when Harry's interactions with his inner darkness feels something along the lines of an erotic drug trip with tentacle bondage.
* EvilLaugh: Harry develops one after learning some nasty curses.
* EvilMentor: Voldemort to Harry.
* TheEvilsOfFreeWill: Dumbledore has been controlling every aspect of Harry's life since before his birth and has become unsettled when things are no longer going according to plan.
* FaceHeelTurn: Harry. By ''Breeding Darkness'' he is a Dark Wizard, through and through.
* FagHag: Fleur agrees to go out with Harry to the Yule Ball because he's the only person she can hold an intelligent conversation with because he's not affected by her Veela aura. She's the first to guess why.
* FallenHero: Harry.
* FalseFriend: Harry feels this way about his so-called "friends." Later Harry to everyone at Hogwarts.
* FantasticTimeManagement: In ''Breeding Darkness'' [[spoiler: in order to attend school at Hogwarts, manage the Death Eaters, continue his independent studies, and spend time with Tom; Harry uses a Time Turner to live every day twice.]]
* FeedTheMole: Dumbledore controlled Trelawney with the imperious to make her spout out a fake prophesy while he knew Snape would be listening in.
* ForWantOfANail
* ForYourOwnGood: This is Dumbledore's excuse for all of his manipulations of Harry.
* FreudianExcuse: Harry was abused by the Durselys, manipulated by Dumbledore and abandoned by his friends. Also Tom Riddle was outed when he attended Hogwarts in the 30s [[BlatantLies so naturally he found friends and acceptance.]]
* FriendlyEnemy: Harry and Hermione after he begins speaking with her again.
* GambitPileup: Voldemort has plans. Harry has plans. Snape has plans. Dumbledore has plans. The results are interesting.
* GirlfriendInCanada: Draco assumes that Harry doesn't really have a boyfriend because this mysterious boyfriend doesn't attend Hogwarts.
* GoodAllAlong: [[spoiler: The Dark Lord's chosen task is to save as many people as he can from the coming Apocalypse.]]
* GoodIsDumb: After four years of knowing him Ron and Hermione ''finally'' figure out that Harry was being abused by the Durselys.
* GreatEscape: Harry helps Voldemort break his followers out of Azkaban.
* HalfHumanHybrid: All Wizards are the descendents of humans that bred with magical creatures.
* [[HeroAntagonist "Hero" Antagonist]]: Dumbledore, [[ManipulativeBastard for a limited value of heroic.]]
* HolyHandGrenade: Harry notes that many of the [[LightIsNotGood light]] and neutral spells can be just as deadly as the dark ones and finds it to be quite [[{{Hypocrite}} hypocrital]] that many spells are banned just because they're "dark."
* HopelessSuitor: Draco for Harry.
* HorrifyingHero: Harry in his [[spoiler: snake]] form saves [[spoiler: Fleur from the Grindelows.]]
* HumansAreTheRealMonsters: [[spoiler: According to the Elves' ancient prophecies Muggles are going to destroy the world.]]
* {{Hypocrite}}: The "Light" wizards. Also [[TheDarkSideWillMakeYouForget Harry becomes the very thing he despises.]]
* IDidWhatIHadToDo: When Hermione complains about the sort of spells Harry is learning he snaps at her that he'll do whatever he has to do to survive the Tournament.
* INeedAFreakingDrink: Snape after he learns that Harry is a Dark Wizard and allied with Voldemort.
* InYourNatureToDestroyYourselves: Well, according to Voldemort [[spoiler: and an ancient elven prophecy]] the muggles are beyond saving...
* IncestIsRelative: Harry discovers he's a distant relation to Voldemort on both sides of his family tree and in fact most of the "pure bloods" are related.
* InfractionDistraction: [[spoiler: Harry conceals his knowledge of Parselmagic by pretending that [[ScaledUp his snake form]] is his animagus form.]]
* ItIsBeyondSaving: Tom [[spoiler: and the Elven Prophecy]] says this of the Muggle World.
* ItsAllAboutMe: Harry's attitude when Ron is banned from Quidditch because, boo hoo-it's not like Ron was there for him when he thought he was going to ''die'' in the Tri-Wizard Tournament.
* ItsProbablyNothing: Hermione notices Harry is changing but just thinks it's stress brought on by the Tri-Wizard Tournament.
* JustAStupidAccent: For some reason the Bulgarian students still just speak English with a heavy accent when alone.
* KidsAreCruel: This is Harry's and Tom's FreudianExcuse.
* KingpinInHisGym: Voldemort and Harry work out in their private gym.
* KnightTemplar: Dumbledore and his "Greater Good."
* LackOfEmpathy: Harry no longer gives a crap about his once "friends."
* TheLastDance: Harry after he's been forsaken by everyone and he's ''sure'' the Tournament is going to kill him.
* LaughingMad: Harry after Rita Skeeter outs him to the Wizarding World.
* LightIsNotGood: Harry believes this and later [[ExploitedTrope exploits]] this [[spoiler: Harry uses the ConspiracyTheory that Dumbledore is the Light Lord and forcing everyone to use light spells so they will obey him to gets Fudge on his side. Also PlayedStraight because there are several things that seem to suggest that ''Harry'' [[ProphecyTwist is the Light Lord.]]]]
* LivingWithTheVillain: Despite his shift in allegiances Harry still attends Hogwarts.
* TheLoad: Wormtail is this to the Death Eaters and Harry considers Ron to be this in his other life.
* LoopholeAbuse: when Harry faces allegations that he "cheated" during the first task of the Tri-Wizard Tournament by [[TalkingTheMonsterToDeath subduing the dragon using Paraseltongue]] Harry points out that nowhere in the rules did it say he had to ''fight'' the dragon.
* LoveMakesYouEvil: [[spoiler: Viktor Krum joins the Death Eaters in order to keep Hermione safe.]]
* MaddenIntoMisanthropy: Harry. Harry becomes disgusted by his school and his so-called "friends." Sure, they'll support him when he's playing hero or won them a house cup but when the chips are down they'll readily abandon him at the first sign of trouble.
* MadeOfIron: [[spoiler: as a consequence of repairing the damage living with the Dursleys has done to his body (using some truly painful methods) Harry has developed a high tolerance for pain.]]
* [[MagneticHero Magnetic Villain]]: Voldemort, [[spoiler: being the magically appointed Dark Lord,]] has this naturally. Also Harry.
* ManipulativeBastard: Dumbledore, Harry.
* MoralityPet: Fleur, Sirius Black, and Hermione to Harry.
* MotiveMisidentification: [[spoiler: Voldemort isn't really trying to wipe out the Muggles because he knows [[InYourNatureToDestroyYourselves they're going to destroy themselves.]] He merely used the Pureblood agenda to build his political powerbase.]]
* MyFriendsAndZoidberg: There's Harry's friends the Death Eaters... and Wormtail.
* NeverTheSelvesShallMeet: When using a Time Turner, Harry feels weird whenever he's in proximity of his past or future self.
* NiceJobBreakingItHero: Dumbledore - [[spoiler: Voldemort's true goal is to save the Wizarding World.]]
* NotSoDifferent: Harry and Dumbledore.
* NotSoImaginaryFriend: [[spoiler: The Horcrux in Harry's head.]]
* OddFriendship: Harry and Fleur, Harry and Draco, Harry and Sirius.
* OutGambitted: [[spoiler: Dumbldore did this with ''everyone'' with the fake prophecy.]]
* TheParagonAlwaysRebels: Harry, and since his FaceHeelTurn he's been subtly corrupting his once "friends" in an attempt to "save" some of them.
* PetTheDog: [[spoiler: Harry saves Fleur from the Grindelows.]]
* ThePowerOfHate: when practicing curses Harry focuses his anger to get stronger.
* ProtagonistJourneyToVillain: ''Harry Potter and the Descent Into Darkness''. It's ExactlyWhatItSaysOnTheTin. Harry is embittered by the abandonment of his friends following the fiasco with the Goblet of Fire [[spoiler: and [[SuperpoweredEvilSide allows the horcrux access to his mind]]]], he finds comfort in his new [[NotSoImaginaryFriend imaginary friend]] who guides him to [[TheDarkArts Slytherin's Library in the Chamber of Secrets]] for guidance on how to survive the tournament.
* ProphecyTwist: Dumbledore's fake prophesy. Also [[spoiler: the Elven Prophesy of the End of Days where the Dark Lord and the Light Lord must work together to save us all. Harry assumes that the Light Lord is Dumbledore but there are several hints (such as his MagneticHero status, his previously strongly light aligned aura, his being known as the Dark Lord's equal...) that the Light Lord is/was actually ''Harry''.]]
* PropheticName: [[spoiler: Harry uses the alias "Notechis" (meaning tiger snake) when buying questionable books. Shortly afterwards Harry learns how to transform into a sea krait, a kind of striped snake.]]
* PsychoticSmirk: Harry, quite frequently.
* ReadingsAreOffTheScale: Harry and Voldemort are both said to have impossibly powerful magical auras.
* SanitySlippage: Harry, especially once he gets a taste of TheDarkSide.
* ScaledUp: [[spoiler: Harry learns how to transform into a sea krait.]]
* ScrewDestiny: [[spoiler: Harry decides to side with Voldemort and not play Dumbledore's games anymore.]]
* SeekingSanctuary: [[spoiler: Harry uses one of the Potter properties, which happens to be an old abbey, as the new Death Eater headquarters.]]
* SexierAlterEgo: Tom has his normal [[{{Bishonen}} handsome]], human form versus the ugly snakey form which he uses as his persona as the Dark Lord so that his followers will deify him. Also Harry uses the Dark Arts for self-improvement.
* SlashFic: It's Voldemort/Harry
* SlasherSmile: [[spoiler: Harry when he has Rita in his clutches.]]
* SlowlySlippingIntoEvil: Harry
* SnowballLie: Harry's lies are not always consistent but [[ManipulativeBastard he always has another lie for why he lied in the first place.]]
* TheSociopath: Harry becomes one.
* StepfordSmiler: after the Tournament, Harry falls back into his "Gryffindor hero" persona to put his "friends" minds at rest so he can more easily spy on them.
* SurpriseIncest: Harry learns he's related to Voldemort on both sides of the family tree. [[VillainousIncest They don't think too hard about it.]]
* TalkingTheMonsterToDeath: [[spoiler: How Harry gets through the First Task of the Tri-wizard Tournament.]]
* TangledFamilyTree: All "Pure bloods" are related to each other and, taken further ''all wizards'' are probably related to each other and the so-called muggleborn are actually the descendents of squibs. Also Wizards initailly came about from humans interbreeding with various magical creatures.
* TeensAreMonsters: Harry's fair-weather friends. Also Harry himself.
* ThemedAliases: Harry has "Notechis Noir", "Notechis" is Latin for "Tiger Snake" and [[spoiler: [[PropheticName Harry eventually gains the abilitiy to turn into a striped snake]]]] and Noir is French for "Black" which he named for his Godfather, Sirius Black. Sirius later nicknames him "Stripe" [[spoiler: for his snake form.]] And later Harry takes on the identity of "Evan Harris." "Evan" comes from his mother's maiden name Evans and "Harris" for [[LastSecondWordSwap in case someone slips up and almost calls him "Harry"]]. Also Voldemort has "Nichodemas Tomaras". Nichodemas means "the people's conqueror" and Tomaras sounds like "Tom".
* ThisIsYourBrainOnEvil: Harry struggles with Dark Magic addiction. Draco recognizes the symptoms.
* TookALevelInBadass: Dark!Harry.
* TookALevelInJerkass: Again, Dark!Harry
* TrainingFromHell: [[spoiler: Harry gets dueling lessons from Voldemort, at the end of which he frequently has to work on reattaching limbs.]]
* TheUnfettered: After he was abandoned by ''everyone'' Harry's one goal becomes "survive the Tri-Wizard Tournament." [[spoiler: After he succeeds with this goal it changes to "help Voldemort prepare the Magical World for the Apocalypse."]]
* UnholyMatrimony: Harry and Voldemort.
* VillainProtagonist: Harry
* VillainWithGoodPublicity: Harry. No one (except for maybe Dumbledore) suspects a thing. Also Dumbledore.
* VillainsOutShopping: In ''Breeding Darkness'' Dumbledore runs into Voldemort and his mysterious new [[TheDragon Dragon]] [=/=] [[UnholyMatrimony boyfriend]] ''literally'' out shopping on a daytrip to Little Hangleton.
* VillainousFriendship: Harry and Barty Crouch Jr. Also Harry and Thorfinn Rowle.
* WeCanRuleTogether: [[spoiler: Harry approaches Voldemort and asks how he might be of assistance. Later Harry offers Wormtail to Sirius if Sirius would take Wormtail's place in serving the Dark Lord. As much as Sirius loves his godson he ''can't'' accept such an offer.]]
* WellIntentionedExtremist: [[spoiler: Voldemort. He's actually working to save as many people as he can from the coming Apocalypse.]]
* WhosLaughingNow: Harry
* WoobieDestroyerOfWorlds: Harry
* XMeetsY: Dark!Harry is like [[Franchise/StarWars Anakin Skywalker]] meets {{ComicBook/Venom}} meets [[Manga/DeathNote Light Yagami]].