Unholy Matrimony



""Once you have frozen mankind, these babies will overrun the globe, and we shall rule them, for we will be the only two people left in the world.""

""Adam and Evil.""

- Poison Ivy and Mr Freeze, Batman and Robin

You know how the story goes, right? The Big Bad meets The Baroness, The Baroness meets The Big Bad, their eyes meet, and horribly discordant music that sounds not unlike the screaming of tortured souls arise. It's black magic... a match made in hell!

Lord Worldbreaker and Lady Firestorm are, individually, serious threats to the heroes, but what happens if they're suddenly working intimately together? That's when it gets really dangerous. A pair of villains capable of channeling The Power of Love is enough to give even the most hardened group of heroes a serious challenge, and worse yet, seeing the villains in love may make them doubt their own motivations. Should one of the villains fall, the other one grieving over their fallen lover is quite likely to initialize an Alas, Poor Villain scenario, and maybe even a My God, What Have I Done?. Should another villain start messing with the happy couple, it's usually played as a Kick the Dog moment.

...of course, these people are villains, so you can never really be sure that one or both of them isn't just playing at being in love, in order to manipulate and use the other. If the love was genuine but unrequited, expect the one who genuinely loved to sacrifice her life to protect the other, only for him to disdainfully ignore her as she lies dying, proclaiming that she's no longer useful to him. Which, of course, makes him the worst kind of bastard imaginable.

If both were faking it, expect them to show their True Colors at the same time. Hilarity Ensues - and it's never mentioned ever again.

The most classic version of this trope occurs when two previously established antagonists suddenly take a newfound interest in each other, but it can also involve a newcomer falling for an established villain, or even a pair of villains who were, from the beginning, a 'villainous couple'. In the first-mentioned scenario, Strange Bedfellows may occur in order to match the united power of the couple (ironic, huh?) - which can get particularly interesting if the 'bedfellow' is another villain, who is driven by jealousy...

May form a Big Bad Duumvirate.

Compare Villainous Friendship, when the two are truly friends with each other, but not in a romantic way. Contrast Minion Shipping and Mad Love. Outlaw Couple is basically the petty crime version of this. In the case of fiction with multiple villains where taking two out of the equation would still leave a bunch of bad guys, if it's genuine on both sides this can be used as a prelude to a Heel Face Turn or at the very least a "Get Out of Jail Free" Card. If the couple in question is heterosexual, expect the man to be the more important half of the couple, possibly making her more of a Dark Mistress.

Anime and Manga

 * In My-HiME, Miyu and Alyssa make a nice couple - so loving towards each other that Mai at first has a hard time believing that they're actually villains. This plays with the trope heavily; it's not a sexual relationship, though it's definitely a loving one,
 * Sensui and Itsuki from Yu Yu Hakusho are a rare homosexual example. Well, sometimes...
 * Hiei and Mukuro seem to have this going by the end of the manga.
 * In Naruto, Pain and Konan are a rather peculiar example,
 * Kunzite and Zoisite in Sailor Moon. Homo or hetero, depending on version.
 * In Death Note, there is, of course, Light and Misa. Just what the Anti-Villain needs: A Psycho Who Works for Free. Then there's Kiyomi Takada. She and Misa have a little subtext argument about who's really his lover. As Near said "Light is popular with the ladies."
 * X and Ai in Majin Tantei Nougami Neuro, a psychotic shapeshifting serial killer and his best friend and lover the terrorist.
 * In Rurouni Kenshin Shishio Makoto and Yumi have a bit of a subversion on this. Yumi legitimately loves Shishio.  Along with Shishio's devoted Battle Butler; he lights up at the thought of going into Hell if it means serving his master.
 * In Overman King Gainer, Siberian Railroad executive Yassaba Jin and his dragon, Adette, are very much in love, and actually make a pretty cute couple. Indeed, Jin's combat-prowess goes up noticeably when he's fighting to prove himself to Adette, rather than just for corporate objectives...
 * Riful and Dauf in Claymore are this.
 * Also Isley and Priscilla.
 * In Umineko no Naku Koro ni, Kinzo and Beatrice are some sort of version of this. Of course,.
 * A more clear-cut example would be.
 * Khyron/Kvamzin Kravshera and Azonia/Laplamiz from Macross / Robotech.
 * from Baccano!. They actually end up quite Happily Married.
 * A joke ending in the DS game has wind up in a just as happy - and far more depraved - marriage with .
 * Debatably, Isaac and Miria also qualify—though they're more in the Plucky Comic Relief Anti-Hero role than anything else.
 * Flame of Recca has Mokuren and Mikoto. They're quite happy until she gets wounded and he decides to just kill her For the Evulz. She probably should have known better.
 * In Shigurui, there's Lady Iku with Seigen to whom she is completely devoted to. It is unclear how much Seigen cares about her, although he does treat her much better (ie. like an actual human being) unlike her previous lover Kogan.
 * In Kagerou Nostalgia Evil Overlord Kiyotaka Kuroda appears to have his wife, Yasha, and his son, as Morality Pets. As the series progresses though, it becomes increasingly apparent that Yasha is every bit as manipulative and cruel as her husband (and he knows it) and their son is both of their Morality Pet. Rikimaru would really love to be this with.
 * Kriem and Jake Martinez in Tiger and Bunny.
 * Dio Brando, a century-old vampire and Enrico Pucci, a morally ambiguous catholic priest make up for a very interesting case in JoJo's Bizarre Adventure. Although it's still controversial if they are this or villainous friends, the author himself has lately confirmed Dio to be into both men and women.
 * Subverted in Fushigi Yuugi. Soi loves Nakago, but he doesn't seem to reciprocate (although he does use her Deus Sex Machina to heal, and generally treats her pretty nicely for a Big Bad of his caliber). However,
 * Hansel and Gretel from Black Lagoon.
 * Hunt and Sarah from Tegami Bachi.

Comic Books

 * While not married to each other, Dormammu and his sister Umar, both major mystic threats, join forces (literally, their mystic power is shared between them) to take ultimate power in a Defenders miniseries. Dormammu spends most of the alliance seeking Umar's approval and Umar finds ways to torment Dormammu. All in all they bicker like a married couple.
 * um...does that really fit the topic?
 * The U-Foes, a Marvel Universe Evil Counterpart to the Fantastic Four (though oddly not Fantastic Four enemies), naturally also included an evil version of the Richards couple: Vector and Vapor.
 * Again in the Marvel Universe, the Absorbing Man and Titania were married. Absorbing Man left her because Titania couldn't let go of her fixation with She Hulk.
 * Even earlier, The DCU has the Sportsmaster and the Huntress, two Golden Age villains revealed to have married when they returned in the 1960s.
 * In Batman, Harley Quinn puts quite a lot of effort into persuading the Joker to enter into this joyous state. She's never quite managed it yet, which is probably to the benefit of all concerned. She does have a semi-regular relationship with Poison Ivy, whenever Mr J throws her out, or tries to kill her or one of them is captured.
 * From the always reliably warped Doom Patrol, we have a rare gay example: The Brain, a disembodied brain who occasionally has a robotic body, and his Dragon Monsieur Mallah, a hyperintelligent French Marxist gorilla.
 * In Captain America, the Red Skull's daughter Sin and her lover Crossbones (one of the Skull's henchmen).
 * In the Yank Wilson story in the first issue of Next Issue Special, Rajiv Bahdgi and his wife Berlin Holiday are... special. Bahdgi's villainous activities have become wild, unfocused, and more destructive than ever since his marriage. When Yank Wilson and his team are sent to apprehend him, we discover why: his overbearing wife has been driving him mad and he wants to be captured just so he can get away. Unfortunately for him, due to the heinous nature of his actions, the government has a special arrangement for him in Leavenworth: he and his wife will be sharing a cell. Cue Big No.
 * In the Crime Syndicate, the Mirror Universe version of the Justice League of America, Superwoman (evil Wonder Woman) is married to Ultraman (evil Superman). But she's totally contemptuous of her husband, and her illicit affair with Owlman (evil Batman) is closer to the trope.
 * In the Sonic The Hedgehog comics, there's Scourge and Fiona Fox. Fiona pulled a Face Heel Turn to be with him, and when Scourge took over Anti-Mobius and made himself king, he made her his queen. They seem to actually care about each other, as several times they've both come to each other's aid when it would have been easier to abandon each other.
 * There's also the Iron Queen and King, who thankfully were just a marriage of political convenience. Though, the Queen did have a thing on the side with Snively, and each seemed to be using each other to advance their positions in Eggman's empire.

Film

 * In Austin Powers: The Spy Who Shagged Me, Dr. Evil and Frau Farbissina have a fling, leading to The Reveal that, thanks to some fun with a Stable Time Loop Time Loop.
 * And of course, before that/after that, Frau Farbissina gets involved with a female professional-golfer-assassin.
 * Sol and Viper, the fun-loving cannibal couple in Doomsday.
 * The Mummy Returns had Imhotep reunite with a reincarnated Anck Su Namun in an unhealthily undead version of Reincarnation Romance. By the movie's climax he's clinging for dear un-life on the lip of a gaping hole to the ancient Egyptian underworld as the Collapsing Lair falls around them and the hero couple. He extends his hands to her for help, and she... leaves. Imhotep turns to the O'Connell's (where Evie did help Rick up) and gives them a heartbreaking smile before letting go. Anck Su Namun got punk killed shortly afterwards, of course.
 * Anck-Su-Namun is even worse in the Animated Adaptation. Which is saying something, considering the movie version threw venomous snakes at people. It's implied in the cartoon that Anck-Su-Namun was just in a relationship with Imhotep for chance at achieving power; after he goes through the trouble of resurrecting her, she abandons him the moment she gets her hands on the Artifact of Doom of the week. When they encounter each other again in the series finale, Imhotep is apparently over her, as he leaves her to rot in the Underworld in an And I Must Scream state.
 * In the sequel to The Crow, The Crow: Wicked Prayer, Luc Crash and Lola Byrne are this trope, and are, by all indications, genuinely in love. Of course, then they go through with their Unholy Wedding Ceremony, and Luc gets possessed by Satan...
 * The Mayflowers, the Card Carrying Villains of the deliciously campy Hudson Hawk, are passionately in love with one another in a way that makes them more villainous and creepy.
 * The only time Darwin loses his Psychotic Smirk is when.
 * Possibly, Magneto and Mystique of X-Men.

Literature
"Martin: They have complementary insanities. Don't justify it with anything more than that."
 * Bibok and Calosta in Esther Friesner's Majyk By Design. On Orbix, Majyk is a psuedo-sentient tangible substance that actually provides the power behind spells. Our hero Kendar may have scads of Majyk, but the two of them together are positively dripping with it. Married wizards and sorcerers have a heck of a time getting divorced if their Majyk doesn't want to separate.
 * In one of the Conan the Barbarian stories, titled The People of the Black Circle, a villainous sorcerer's lover convinced him that he should betray his four masters and Take Over the World on his own..
 * Odiana and Aldrick in Codex Alera. One is an insane water witch, the other is a brutal mercenary. They are also absolutely devoted to each other and every scene of them being together is filled with such tenderness, love, and overt passion for each other that you could easily forget the horrible violence they are perfectly willing to inflict on anyone else.
 * In Harry Potter, Lucius Malfoy is a bigoted terrorist who uses his money and power to manipulate others, while his wife Narcissa is a just-as-bigoted snob; yet as the series goes on it becomes apparent that these two's love for each other (and their son Draco) is their strongest and most (well, only) redeeming quality; as Voldemort begins to show just how little he regards any of them, their love for each other over him results in the family's practical Heel Face Turn.
 * Vernon and Petunia. They're selfish and abusive to Harry, yet they seem quite devoted to each other.
 * This is exactly what goes on between Voldemort and Bellatrix Lestrange...in the latter's twisted and hopeless dreams, of course.
 * Dangerous Liaisons has as its protagonists the amoral and sociopathic duo of Valmont and Merteuil, proving that this trope is Older Than Radio
 * Poppy Z. Brite's novel Exquisite Corpse RUNS on a gay version of this trope. Andrew Compton and Jay Byrne are necrophiliac serial killers who scheme to murder and eat the secondary protagonist.
 * Caine and Diana from Gone (novel), by Michael Grant. He's a megalomaniac, power-hungry sociopath. She's a deceptive, selfish, manipulative girl who has betrayed just about everyone at some point. And yet they're in love, prompting him to By Plague, though,
 * Norman and Sandra Arminger from the Emberverse. He is ruthless, imaginative, and a powerful warrior; she is cool, brilliant and manipulative. Together they form and control the Portland Protective Association, a medieval recreation/protection racket that seizes control of a huge chunk of the Pacific Northwest after the Change destroys most modern technology.
 * Stirling likes this trope: his Nantucket trilogy features the appalling partnership of deranged sadist Alice Hong and her husband William Walker, a genocidal warlord.
 * The Dresden Files has Esteban and Esmeralda Batiste, nicknamed "The Eebs," who are a husband/wife assassin team for the Red Court. Susan thinks that their relationship is romantic in an incredibly warped and psychotic way.


 * Always pay attention to Martin, he's not necessarily trustworthy but he's definitely a cold-eyed realist and very perceptive and intelligent.
 * The Red Court itself includes Duchess Arianna, an ancient Mayan vampire who turned and married the Spanish Duke Paolo Ortega in revenge for what he and his men had helped do to her people.
 * Which is nothing compared to the lovely activities Nicodemus Archleone and his wife Tessa come up with.
 * Arguably, this trope could apply, at least loosely, to Nicodemus and Dierdre, daughter of Nicodemus and Tessa. Yes, that means what it sounds like.
 * Black-magic users Isaac and Selena Izzard in John Bellairs' The House With A Clock In Its Walls, although they're both already dead by the time the story actually starts.
 * Red Seas Under Red Skies has Requin and Selendri. He's the vicious head of a casino where anyone suspected of cheating is put to death; she's his Two-Faced top enforcer. They are both absolutely devoted to one another, to the point where Requin hideously burned his hands trying to scrape off the contact poison that led to Selendri's current condition, then did something unnameable to the man who took out the hit.
 * In Death series: This has happened a couple of times, like in Salvation in Death and New York to Dallas. However, in those cases, one of the couple is genuinely in love and the other has nothing but contempt for the other. The contemptuous one will murder the other one, thereby crossing the Moral Event Horizon...if s/he has not already done so!
 * Sisterhood series by Fern Michaels: A number of stories has this going on between the bad guys, like in Lethal Justice, Vanishing Act, and Deadly Deals. However, the "love" between such couples is apparently not genuine, and they will inevitably turn on each other once the Vigilantes and Karma start closing in on them!

Live Action TV

 * Angelus and Darla of Buffy the Vampire Slayer and Angel fame. Darla was a Complete Monster to begin with, but once she teamed up with Angelus, the duo started traveling the world, staying wherever a genocidal civil war was currently going on. Those were the only places they would not have to restrain themselves too much without being discovered.
 * Likewise, Spike and Drusilla, who seemed to be genuinely in love, albeit still quite psychotic. Sad it didn't last through all of the seasons. Spike's later relationship with Harmony counts as this as well, though it rather notably doesn't really work quite so well and doesn't last nearly so long, for more than one reason.
 * Lindsey and Eve off Angel too.
 * YMMV in regards to Angelus and Darla. It was stated that Angelus was not capable of actual love, and Darla was quick to sell him out in a tight spot (they were trapped in a barn with vampire hunter Holtz and his followers outside and one horse. She hits him over the head and rides off on the horse.)
 * But when he catches up with her he makes her "pay for her sins. Again and again." And then they get back together. And when Angelus is trapped and tortured by the same man, Darla sets up a rescue party.
 * Happens two times during Power Rangers
 * In Mighty Morphin Power Rangers, Lord Zedd and Rita Repulsa actually went as far as subverting the inevitable failure of the Love Potion - and eventually getting married. Later its revealed that Zedd loves Rita for real, when he is exposed to an antidote against the love potion. The behind-the-scenes reason for this Unholy Matrimony is that the Moral Guardians thought Zedd, acting as an evil overlord, was too scary for kids during his early run. Therefore the producers toned him down by making him part of a bickering married couple.
 * This is why Space Pirate Divatox wanted to release Maligore in the Power Rangers Turbo movie. She started having second thoughts after getting a good look at him, seeing that he is a berserk fire demon.
 * Anita and Roger Roycewood, the couple of  from Criminal Minds.
 * A couple in Dexter show up as Victims of the Week, telling each other that they love each other even while Dexter is about to kill them for murdering several innocent immigrants.
 * Vlad and Lizzie the vampire couple from The Middleman.
 * Even though he's the protagonist, Alan B'Stard and his wife Sarah in The New Statesman are both amoral and power-hungry enough to qualify for this trope. (They take the idea of a "love-hate" relationship to whole new levels...)
 * Over the course of Hercules and Xena, Ares has been romantically involved with both Callisto and Hope, even impregnating the latter.
 * Inverted in The Vampire Diaries - Damon loves Katherine but she's more interested in his little brother.
 * Lois and Clark had a rich Sickeningly Sweethearts couple who kept their marriage alive by brewing evil plans together.
 * In Nikita, it's eventually revealed that Amanda is in a secret alliance/relationship with Ari Tasarov; together, they plot against both the protagonists and their respective superiors, in order to gain more control and power for themselves. Even after their master plan fails, it's shown that they actually do truly care about each other. One could even argue that their relationship itself is an Evil Counterpart to the one between Nikita and Michael.
 * In Sword and Fairy, this is the case with a snake and fox-demon couple. The snake-demon sacrifices himself on behalf of his wife, who then devotes her powers to preserving his soul.

Music

 * The Ax Crazy couple in "A Little Piece of Heaven" by Avenged Sevenfold.
 * Precisely 50% of the songs on Seanan McGuire album Red Roses and Dead Things are about this trope, with varying degrees of creepiness.
 * "Lucifer" by Blutengel.
 * A lot of Ordo Rosarius Equilbiro's work fits this trope. Especially "Do Lust and Murder Make Me a Man?" and "Let the Words of My Murder Be the Last Words You Hear."
 * "Killers in Love" by Tub Ring.

Mythology

 * Typhon and Echidna from Greek Mythology. She's a beautiful woman with the lower body of a snake, and a fondness for eating travellers. He's a giant with one hundred dragon heads, and a tendency towards deicide. Together they sired the Hellhounds Orthrus and Cerberus, the Chimera, the Nigh Invulnerable Nemean Lion, the Sphinx, and the nearly unkillable Hydra. It becomes even better if you realise that among the Greek pantheon they're probably the two deities/monsters who are the most faithful to one another; there are no reports of either sleeping around (admittedly, when you look like that...), in sharp contrast with Zeus, who to say the least, Really Gets Around. Truly a match made in Tartarus (who is coincidentally, their father).

Tabletop Games

 * From Warhammer Fantasy Battle, the vampire couple Vlad and Isabella von Carstein. After turning Isabella into a vampire he raised a giant army of the undead and they tried to conquer The Empire. As you do. When Vlad was slain Isabella committed suicide.
 * In gameplay, if you have both on the table and Isabella is killed, Vlad goes completely insane, picking up Hatred of the enemy army and Frenzy. Translation: he charges directly at the enemy lines and tries to rip apart the bastards that killed his wife with his hands and teeth.
 * From Dungeons & Dragons, Count Strahd Von Zarovitch believes that
 * From Deadlands fluff, we have Miles and Mina Devlin, ruthless railroad barons, dark sorcerers, devoted spouses and loving parents.

Theater

 * In the Opera Nixon in China, Mr. and Mrs. Mao Zedong are largely portrayed as a loving and romantic, if occasionally disturbing couple. The song "The Chairman Dances" is described by the composer as an outtake from the opera, and is dedicated to this trope.
 * Sweeney Todd: The Demon Barber of Fleet Street: Sweeney Todd and Mrs. Lovett has shades of this, even though they're not married and she's the only one who wants a Relationship Upgrade.
 * Thénardier and Madame Thénardier
 * Though how deep the love goes is questionable. "I used to dream that I would meet a prince- but God Almighty have ya seen what's happened since?!"
 * In Twelfth Night, Toby and Maria spend a lot of time together preparing Batman Gambits in order to make fools of others,.

Video Games

 * To confront and expose the Big Bad in Baldur's Gate, the characters first have to get an invitation to his inauguration ceromony in the Duke's Palace. They get one from the two assassins Slyth and Krystin who hang out in the Undercellar brothel before they get to kill the remaining dukes. These two seem quite crazy and nauseatingly in love, and manage to put up quite a fight when you encounter them for the first time.
 * In the sequel you can cause this. There is two characters talking about how their familes are driving them apart since they're a bad influence on each other. One of your options is to be a Love Freak and tell them that they should run off together. They thank you and tell you everything they do shall be in your name. Later you overhear a conversation about those two. Turns out they were an Outlaw Couple and are now robbing people in your name.
 * Alice and Decus of Tales of Symphonia: Dawn of the New World, with the "one playing the other" thing (gender-flipped). Of course, when Decus becomes a Love Martyr, that changes everything...
 * Oda Nobunaga and Nouhime in Sengoku Basara. Nobunaga is a Complete Monster of an Evil Overlord, while Nouhime is his Love Martyr Psycho Supporter. On Nouhime's death, Nobunaga deems her worthless.
 * Nobunaga and Nouhime have a similar relationship in Samurai Warriors starting from the second game. (In the first, she struggled between killing him and killing for him.)
 * Overlord gives you a choice in Mistresses, though there's always one that's actually relatively non-evil and arguably the Only Sane Person in this Crapsack World. First game featured the prim and proper Rose and the greedy and slutty Velvet. The second game (which confirms as the canon choice) offers Victorious Childhood Friend Kelda, Gold Digger Juno and.
 * Subverted in World of Warcraft, where the quarreling demon couple in Acratraz lets the heroes attack them one at the time while the other provides snarky commentary.
 * Deathwing and Sintharia. However, they were only together because she was the only one of his consorts strong enough to survive the mating after his Face Heel Turn. Also during the earliest days of the Cataclysm Beta there was datamined info that Deathwing was going to corrupt Alexstrasza the Life-Binder and together they would conquer the world.
 * King Ymiron and Queen Angerboda, the leaders of the villainous Vrykul.
 * Sally Whitemane and Renault Mograine, the overseers of the Scarlet Monastery.
 * Malygos and Saragosa. Killing Saragosa and then taunting Malygos over Saragosa's corpse earned the red dragon Keristrasza a Fate Worse Than Death at the hands of a Berserk Button Aspect of Magic. And then death, too, in The Nexus.
 * Lady and Killer from Shadow Hearts: From the New World. Though whether the latter was actually in love or merely Mind Controlled is debatable.
 * In Knights of the Old Republic, Bastila suggests this possibility to a male Player Character near the end. You can take her up on it.
 * If they had actually finished the second game, this would have been possible with whichever love interest you chose on the dark side path.
 * A possibility with Blackguard Aribeth and the player in the end of Neverwinter Nights Hordes of the Underdark; or if you pick the evil path in Neverwinter Nights 2 Mask of the Betrayer the player and Gann/Safiya (depending on gender).
 * Before it was cut, a female player and Bishop in Neverwinter Nights 2.
 * Certain mods do have examples, including Vico and the player in A Dance With Rogues and Alex and the player in The Bastard of Kosigan.
 * LeChuck tries to do this in Tales of Monkey Island Chapter 5: Rise of the Pirate God,
 * Before that, it is discussed at the end of Chapter 4,
 * Soltier and Lapis of Blaze Union. This, along with the fact that they're Anti Villains, helps to earn them Redemption Equals Life in one of the game's endings. Their feelings for each other are both very mutual and very genuine.
 * While not exactly the main vilains, William and Annette Birkin in Resident Evil 2 seem to be a happily married couple of scientists. Mad Scientists!
 * Black Scorpion and Solver Mantis seem to have this sort of relationship in City of Heroes.
 * Traffic Department 2192. Near the end of episode 3, Generals Talon and Marilith are not only lovers, but conspiring to murder the other generals, Kreel and Orlok, in contention for the position as the Overlord's successor.
 * Caster and  in Fate/stay night.
 * Being made by BioWare - and a direct sequel to the Knights of the Old Republic games mentioned above - it comes as no surprise that the MMO Star Wars: The Old Republic has this. The main example is Darth Malgus, one of the main villains, who's happily married to a cute Twi'lek (ex-)slavegirl. The fact that he treats he like a wife rather than a slave is a source of annoyance to the largely xenophobic empire, but since he refuses to play politics and spends most of his time on the Imperial Fleet fighting (and mostly winning) battles for the Empire, it's largely ignored. That, however, does not mean that their apparently genuine, two-sided love doesn't wind up with a tragic ending...
 * Of course, it's also possible for a 'Darkside' player character to start a relationship like this, with an equally-evil companion. Perhaps the most poignant of these options is the Male Sith Warrior, who can  Awwww...
 * On the other hand, if you play your cards right, it's also quite possible for a Darkside player to start and maintain a relationship with a 'Lightside' companion, and acting genuinely carring towards him/her even as you slaughter innocents and inflict pain and misery left and right. Which creates a whole 'nother spin on this trope...

Web Comics
"Roy: Who does the green line represent? Deva: A hypothetical offspring of Cruella de Vil and Sauron."
 * In the webcomic Cheshire Crossing - which is essentially a Massive Multiplayer Crossover among The Wizard of Oz, Alice in Wonderland, Peter Pan and Mary Poppins, with a couple of historical characters thrown in for good measure - The Wicked Witch of the West finds her way to Neverland, and after meeting up with Captain James Hook, the two start a rather *intimate* partnership. This also effectively turns her into a witch-pirate, or maybe pirate-witch, which is awesome. Pirate.
 * In The Order of the Stick, Nale's girlfriend, Sabine, is a succubus - truly a match made in hell (or the Abyss if you want to get technical). Their love is literally maintained through black magic and human sacrifice. And shapeshifting. While often played for laughs, there actually does seem to be a more serious side to their relationship which one can sense when Sabine talks to Vaarsuvius.
 * Later strips would emphasize just how much Sabine cares for Nale;
 * Also, it can even make a secondary unit of measure (in this case, a constant level of evil of 4.8 kilonazis with 0.4 kilonazi deviation):

"Trudy: We both had this... appreciation for the sadistic and morbid. We enjoyed our evil pranks so much that we quickly fell deeply in love with each other. It was black magic."
 * During a Flash Back sequence in General Protection Fault, it's revealed that Trudy - chessmaster and Puppet Master extraordinaire - had a 'teamup' like this during college, with an equally despicable individual named Trent, who later became her archnemesis when he betrayed her.

"Gil: (stunned) You... like him? You... like... you - ?! Wahahahaha! Of course you do! He's a bloodthirsty, treacherous killing machine!"
 * Subverted in Episode Five of the webcomic Demonology 101, when
 * Minions At Work: Leading up to it.
 * Narbonic:
 * Axel and Aerith in Ansem Retort. Axel's a homicidal evil Buddhist god and Aerith's a conniving bitch who actively used Axel to get revenge on Cloud. And she admits to having a murderer fetish.
 * In Kevin and Kell, Angelique is accidentally set up with R.L. after someone hacked into the Flea Bay website for a grooming date. R.L. plans on eating Angelique at the end, but becomes enamored with her after hearing Angelique brag about cheating on Kevin during their marriage, and managing to get him to pay her alimony despite initiating the divorce. The two soon marry after Angelique gives R.L. secrets on catching rabbits. Even when R.L. was missing (presumed dead) and Angelique took over Herd Thinners, restructuring it and using it as a stepping stone to conquer the world, he wasn't bitter. He just pointed out what a headache world conquest was. Angelique agreed to just make loads of money instead. And when the two shared a prison cell, they were just happy to be together. The only thing they needed beyond each other to be happy was their kids.
 * "Black Hat Guy" and...his...um...girlfriend in Xkcd.
 * Brian and Angelo in Our Little Adventure.
 * Didi and Gogo in Bomango playing a Sweeney Todd adaptation Fine young cannibals. Aren't they a cute pair?
 * Occurs between Mad Scientists Spencer Ecchs and Ada Byon in Patchwork Champions.
 * In Sluggy Freelance, it looked like Crushtro and Monicruel were heading this way, until Chestro, his real wife, arrived. If she's not eviler than them both, she's at least more wrathful, and knows how to hit a cheating husband where it hurts—his criminal conglomerate.
 * Jadis the White Witch in the Mega Crossover fancomic-verse the Building-verse is prone to have such relationships. Her ex in the backstory of Roommates is the Erlkönig and she is currently together with Darkness the Prince of Darkness in Girls Next Door (her a son from the first relationship doesn't need enemies: Has two parents from hell and a stepfather he loathes with passion).
 * Girl Genius had a mini-arc "Bang Falls in Lurve!". That being cheerfully murderous Bangladesh DuPree, Vole's vision about "unleashing an ocean of blood!" was what did it to her.

Web Original
"The Author: Then by the power invested in me by myself, I now pronounce you husband and wife. You may kiss the bride, though I would prefer if you didn’t."
 * Some examples in the Whateley Universe, natch. Some of the Bad Seeds (a clique you can only join if at least one of your parents is a supervillain) go to Whateley Academy. Nephandus has as parents The Troll Bride and Hexmaster. In a slight subversion, they're regarded as the Battling Bickersons of the supervillain world.
 * Voldemort and Bellatrix Lestrange in A Very Potter Musical.
 * You could also say in a Ho Yay sense for Voldemort and Quirrell, especially since later in the play
 * Trixie and Prince Blueblood in story 2 of the My Little Pony Friendship Is Magic fanfic "Legion of Gloom". Not only is their dating considered one of the Squickiest things in the fic in-universe, their marriage ceremony is...well...

Western Animation
"Slo-Mo: I like a man who does it fast. Nanosec: I like a girl who takes it slow."
 * In the Transformers Animated episode Society of Ultimate Villainy,a new villan shows up called Slo-Mo, who can slow things down. She apparently also can reverse aging, as she did with Nanosec. She and Nanosec flirt with each other throughout the episode. Swindle stealing Slo-Mo's timepiece (the source of her power) is a definite Kick the Dog for Swindle.


 * In an episode of Kim Possible, Dr. Drakken manages to charm DNAmy into cooperating with him. While Amy seems remarkably responsive to his cheap pickup lines, the most interesting thing about this single-episode teamup is probably that Shego seemed to be downright jealous...
 * At the end of the episode
 * One episode of Care Bears had Professor Coldheart convince villainess Auntie Freeze he wanted to marry her, and asked the Care Bears for help throwing the wedding. The gullible Care Bears agreed, of course, reasoning that anyone capable of Love can't be bad. The reason was to sneak in an organ loud enough to destroy the cloud kingdom and crash the bears down to Earth, but when Auntie figured out it was a sham, she just twisted his ear and led him off to receive punishment...
 * In Gargoyles, Xanatos and Fox make for an Affably Evil - or, after their shared Heel Face Turn, Affably Magnificent - couple. The fans love 'em.
 * Same deal for Demona and Thailog, until they broke up. (The relationship cracked when he threatened her daughter - and shattered completely when he revealed he had a concubine cloned from her.)
 * Azula tries to invoke this with Chan, a guy she meets at a party in the Beach/Villain Episode of Avatar: The Last Airbender, openly stating that she plans to conquer and rule with him by her side, since Chan is a Jerk Jock but not a power-mad sociopath, he's predictably terrified.
 * Sequel Series The Legend of Korra gives us first the incongruously sweet dynamic between Badass Abnormal Arc Villain Zaheer and towering pyrotechnic Brute P'Li, then the more subdued example of Knight Templar city-guard-turned-would-be-dictator Kuvira and Evil Genius Baatar Junior.
 * When Wuya and Chase Young team up in Xiaolin Showdown, they just seem to be standing a bit... close together, for being just allies. Arguably, though, it was just Wuya standing close, and Chase not moving.
 * On Cyberchase, Hacker and Wicked have an on-again, off-again partnership. They seem to be genuinely attracted to each other, but they'll also stab each other in the back the moment they think they can get away with it.
 * An example of two villains who are a couple from the beginning is Boris and Natasha of Rocky and Bullwinkle.
 * Another one is the Monarch and Dr. Girlfriend of The Venture Brothers (they get married at the end of the second season ).
 * Johnny 13 and Kitty from Danny Phantom
 * Also, though not nearly as blatantly, Skulker and Ember.
 * And, "The Ultimate Enemy" reveals that the Lunch Lady and the Box Ghost have a Kid From the Future together.
 * King Sidorak and his Viceroy Roodaka in Bionicle: Web of Shadows (yes, a No Hugging, No Kissing franchise - blame the Promoted to Love Interest trope). Sidorak does seem to have a fondness for Roodaka (which could be taken as strictly platonic), but he mainly offers her his throne as a way to slake her power-lust and keep her out of trouble. She, on the other hand, realizes that under the right circumstances, once she's Queen he becomes expendable...
 * In El Tigre this happens between Puma Loco and Sartana of the Dead. It seems that both of them are faking it at first, but towards the end it is revealed that Puma Loco does holds a torch for Sartana. It gets a little Squicky as Puma is human while Sartana is a walking skeleton. Word of God says that they had a son together, though their relationship was on and off.
 * Destro and The Baroness from G.I. Joe. They had a rather established relationship by the third miniseries and in the comics, they had been together since before they joined COBRA. In the comics, whenever one has been in serious danger, you'd best be prepared to get out of the way of the other because they will stop at NOTHING to ensure each other's well being.
 * An episode of Phineas and Ferb featured Mad Scientist Doofenshmirtz dating a woman just as evil as he was. They even got a song together, though the relationship unfortunately doesn't work out, thanks to Doof's evil-plot-of-the-week coming back to bite him in the butt.
 * Anti-Cosmo and Anti-Wanda on The Fairly OddParents.
 * Mac and Molly Mange of Swat Kats. They were powerful gangsters and married before they died the first time and when they came back as robots, they quickly cheered over their new strength, durability and firepower. Yeah, they bickered a lot, but when one of them got hurt, you can bet your aft that the other would drop everything to save them.
 * Scar and Zira from The Lion King.
 * Some older fans of Wild Kratts sense a bit of Belligerent Sexual Tension between Zack Varmitech and Donita Donata; they even went out on a date in canon. Although, if there is any actual attraction, it seems one-sided on Zach's part.
 * Chief from Pucca, head of the local Quirky Miniboss Squad, has a crush on Garu's enemy Tobe. In one episode they became this trope after Tobe got hit by one of Cupid's arrows, and they had a little love montage showing them robbing stores together and so on. In fact, before the stuff wore off they were this close to getting married.