'''Basic Trope''': A character who is initially heroic slowly becomes as evil or amoral as the things they fight.
* '''Straight''': Norbert is a SerialKillerKiller who becomes a pitiless KnightTemplar as he continues to kill more of his enemies, ultimately becoming no different from a regular SerialKiller.
* '''Exaggerated''':
** Norbert ices one bad guy and instantly [[FaceHeelTurn becomes one]].
** Norbert vows to [[HunterOfMonsters hunt down bloodthirsty beasts]] plaguing the world, he gradually becomes more and more bloodthirsty until he [[AndThenJohnWasAZombie becomes a beast himself]].
** Norbert eventually suffers from severe MotiveDecay and starts killing millions [[ForTheEvulz for the sake of evil]], turning him into a CompleteMonster.
* '''Downplayed''':
** Norbert goes from being a [[IdealHero traditional hero]] to a typical AntiHero as he fights more enemies.
** Norbert goes from a BullyHunter to bullying everyone in school.
* '''Justified''':
** Norbert, despite his justifications, in truth has always had deeply dark desires and urges to punish the people who he saw as evil, even when he was the one who was the victim. Being able to finally kill the people he hated satiated his bloodlust that he was always able to hide behind a veneer of decency, but eventually faded away when he realized he could get away with his cruelty and be hailed a hero for it...until he couldn't anymore. By that point, people were too busy trying to justify enabling his cruel actions and [[NeverMyFault saving their own hides from persecution]], and Norbert was too entrenched in his own selfishness to stop.
** It's a CrapsackWorld where ruthlessness is [[EvilPaysBetter rewarded]] and NoGoodDeedGoesUnpunished.
** [[WhatIsEvil He is starting to doubt the existence of morality due to the existence of these monsters, while cynicism and pure desire takes over.]]
** The constant fighting leaves its scars on Norbert, physically and [[SanitySlippage mentally]]. He becomes increasingly brutal and ruthless because ''[[ShellShockedVeteran that's what happens to someone]]'' when they're going from one battle to the next and ThereAreNoTherapists to keep them from SlowlySlippingIntoEvil, or at least [[TookALevelInJerkass slowly slipping into jerkassery]].
** BlackAndWhiteMorality [[GrayingMorality slowly shifts to]] GreyAndGrayMorality[[note]]Or maybe even EvilVersusEvil[[/note]] during the battles, turning Norbert mad from doubt about what he is doing.
** He's heard too many [[BreakThemByTalking breaking speeches]] from the villains he's taken down, and they're starting to stick.
** Norbert is catching TheVirus from his kills.
** Norbert was a sociopath to begin with, but [[VillainWithGoodPublicity kept up appearances as a hero]] and got hired to hunt monsters due to his skills. As the years go by, he slowly lets his ugly side out more and more until it was all that anyone could see.
** The monsters in question, when dispatched, [[YouKillItYouBoughtIt can transfer some of their monstrous energy to their killer]]. Since Norbert is a dedicated monster-hunter, it's little wonder that he [[KlingonPromotion absorbed a bit too much of the monstrous essence]].
* '''Inverted''':
** HeelRealization.
** Norbert set out as a [[NinetiesAntihero bloodthirsty]] [[UnscrupulousHero ruthless]] VigilanteMan inflicting violent punishments on criminals; however, seeing the pain and horror brought by him, he became TheAtoner and pushed for peaceful resolutions of conflicts whenever possible.
** ContagiousHeroism: Norbert used to be a career criminal with little to no regard to the victims of his misdeeds, but after all the time [[RecruitingTheCriminal spent on duty]] with [[AlwaysGetsHerMan Inspector]] [[TheHeroine Alice]] he transformed into a man of virtue, compassion and high moral standing, possibly even [[ReformedCriminal abandoning crime altogether]].
** Emperor Evulz started out on the edge of being a CompleteMonster, but he becomes steadily more noble and honourable as he fights the heroes, until at the end he has become a HeroAntagonist.
* '''Subverted''':
** Just as his violent impulses start to manifest, Norbert's TrueCompanions remind him of his goals and virtues, thus preventing him from going too far astray.
** Upon seeing the aftermath of his violent streaks, Norbert [[MyGodWhatHaveIDone feels a wave of horror, guilt and remorse]].
** Norbert doesn't ''become'' evil. [[EvilAllAlong He was]] ''[[EvilAllAlong always]]'' [[EvilAllAlong evil]]. He's just gotten worse at controlling his impulses and/or justifying his actions, so his MaskOfSanity [[VillainousBreakdown is starting to slip]].
** Norbert simply lays down his sword and goes home when the last monster is slain, after taking extensive care to [[NeverHurtAnInnocent avoid any collateral damage along the way]]. After all, the whole ''point'' of fighting monsters was to stop them and perhaps MakeAnExampleOfThem to others who aspire to monsterhood. What does it say about ''[[PsychologicalProjection you]]'' that you consider killing monsters [[NotSoSimilar morally]] [[DesignatedEvil comparable]] to killing their victims? DidYouActuallyBelieve [[AboveTheInfluence he'd lose sight of his goals that easily?]]
* '''Double Subverted''':
** He gets separated from his friends during a mission and, without anyone to keep him in check, is immediately consumed by his own bloodlust.
** However, [[IgnoredEpiphany he dismisses the unpleasant reflections]] time and time again, to the point of a TautologicalTemplar.
** Despite his immorality, Norbert [[EvenEvilHasStandards wouldn't cross certain lines]] before going on his crusade. Now, he's slowly getting closer to becoming the worst kind of monster.
* '''Parodied''':
** Norbert starts to look and speak like his enemies, and by the end of the story, it's impossible to tell who's Norbert and who's the enemy.
** Norbert writes a note to a bad guy telling him to stop being evil, Norbert then immediately kills random people for no reason.
** Norbert is a BullyHunter who automatically becomes TheBully.
** Norbert defeats a {{TabletopGame/Chess}} champion, but in doing so became a chess champion himself. He is [[FauxHorrific horrified]] by [[WhatHaveIBecome what he has become]].
* '''Zig-Zagged''': Norbert's morality seems to jump between good and evil whenever he kills a monster.
* '''Averted''':
** Norbert is unchanged by his work.
** Norbert was ''always'' evil, and only targets [[EvilversusEvil people worse than he is]] as a way of trying to keep the heat off himself.
** Once Norbert has gotten his revenge, he does, in fact, stop fighting.
* '''Enforced''':
** "[[ThouShaltNotKill We can't have one of the good guys killing people]]. Let's make him one of the bad guys instead!"
** The author is writing a {{Tragedy}}.
** "HumansAreTheRealMonsters. Let's show how the humans slowly become the very evil they sought to kill to enforce AnAesop on how {{Humans|arebastards}} and [[AlwaysChaoticEvil Monsters]] are the same."
* '''Lampshaded''': "I regret that I have to say it, Norbert, but after all the things you've done... You and [[BigBad Evulz]] are {{not so different|remark}} anymore!"
* '''Invoked''':
** SerialKiller Alice knows that, eventually, she's going to be caught by Norbert. She kills his little sister in order to make Norbert more like herself as revenge.
** Norbert is killing the monsters for the ''sake'' of becoming one, either physically or mentally.
** Norbert is being influenced by Emperor Evulz subconsciously.
* '''Exploited''': A ManipulativeBastard uses the fact that Norbert is turning into a villain to create discord within TheTeam which Norbert is part of.
* '''Defied''':
** [[TheFettered Norbert]] [[HeroicVow vows]] to never become like his enemies, even if it means subjecting himself to a FateWorseThanDeath.
** "[[WarIsHell It's war]], and if you want to survive and win, [[ShootTheDog you have]] [[ViolenceIsTheOnlyOption to be]] [[TheRevolutionWillNotBeCivilized just as brutal]] [[BeatThemAtTheirOwnGame as your enemy]]."
** "Oh, you're gonna give me this damn speech about 'WhatIsEvil' and how me kicking your ass makes me just as much of a monster as you are? '''[[NOYou You're]]''' the asshole that killed a thousand people, raped a hundred, terrorized the entire country, and now you're here attacking a school; all because [[HopeCrusher you literally hate hope and anything that represents it]], even little girls that have done you no wrong other than existing and having the name "Hope", and ''giving you a concussion'' makes ''me'' a monster?!? '''''[[ShutUpHannibal COME ON!!!]]'''''"
* '''Discussed''': "Well, what did you expect? Norbert was always the best at his job."
* '''Conversed''': "If you are planning revenge, don't. You'll become exactly like your enemies, like what happened in this show."
* '''Deconstructed''':
** Every day, his foes show him new depths of horror, keeping him on the straight and narrow.
** [[WoobieDestroyerOfWorlds Norbert]] has ''tried'' being good, fighting back against evil while maintaining the moral high ground. Unfortunately, in this setting GoodIsImpotent: AdultsAreUseless, PoliceAreUseless, MilitariesAreUseless, {{Cardboard Prison}}s are the norm so imprisonement is all but worthless, the government is made up of {{Lawful Pushover}}s, and [[ThouShaltNotKill the other heroes]] [[KillHimAlready keep allowing the villains to live]] so they could [[ViciousCycle resume their mayhem another day]]. He realizes that BadGuysDoTheDirtyWork and that it TakesOneToKillOne, so he decides to swear off the IfYouKillHimYouWillBeJustLikeHim lesson and [[ThenLetMeBeEvil willingly embraces becoming evil]] to put an end to the monsters he sees.
** Norbert is very conscious of this trope and is constantly examining himself and his actions because he is so afraid of sliding down the slippery slope and into the deep end, and the keepsake that he always carries with him that is directly tied to the original event that started his fight against evil is there to remind him of why he's fighting, lest he fall victim to MotiveDecay.
* '''Reconstructed''':
** The depression caused by what he sees causes him to [[DespairEventHorizon despair and]] [[ThenLetMeBeEvil give in to evil]].
** While Norbert may destroy other villains, he doesn't actually reduce the evil in the world, but fill in the vacuum they have left behind. He may try to [[PayEvilUntoEvil concentrate his efforts on other villains]], but his unscrupulous methods [[DestructiveSavior endanger many innocent lives as collateral damage]]. He eventually becomes a KnightTemplar that crosses the MoralEventHorizon, and is forced to be put down by the heroes. [[NecessaryFail They realize the fault they have in Norbert's descent into evil]], and vow to better themselves so that no more desperate people follow his path.
** Norbert fell off the slippery slope a long time ago, but absolutely does not see it, and his self-examinations and questioning are worthless because they are being filtered through the lens of someone who cannot recognize the reality of what they are doing. Oh, and that keepsake? It makes him worse, as it feeds into his increasingly dogmatic mindset and allows him to find a way to connect everything he does to his original cause and thus justify it, no matter how tenuous a connection (if there even is a connection, half of it is all in his head) it may be.
* '''Played Literally''': AndThenJohnWasAZombie
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%% Optional items, added after Conversed, at your discretion:
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%%* '''Implied''': ???
%%* '''Played For Laughs''': ???
%%* '''Played For Drama''': ???