Bakura: Marik, I... I hate you. I hate you with all my heart. I hate you more than I've ever hated anybody. I hate you so much I can barely take it. In fact, I want to go on hating you for the rest of my life...
Marik: Oh, Bakura! I had no idea you felt that way about me! I-if it makes you feel any better, I hate you too. I think I hated you from the moment I first met you.
Bakura: In that case Marik, if we win this duel, let us go and make sweet hatred together. Just you and me. Hating each other. All night long.
Two foes who fight in close combat, constantly obsess over their next battle with one another, and spend all their time thinking about one another can't possibly be more than "just enemies" right? No Way!
After hearing Naoi's life story, Otonashi hugs him, despite the former having massacred his friends and having planned to hypnotize them into disappearing. Naoi then becomes Otonashi's fanboy.
Yuri and Kanade have a bit of this.
A half human half spider hybrid appears in the first OVA of Angel's Feather. When he appears he wraps Shou up in his web, caresses him, gets close to his face, sticks his finger in his mouth, and licks him before trying to murder him. Shou blushes in response to all of this.
Upon learning that Annie was the female Titan, Eren went into a denial so deep he was unable to transform to fight her, even after watching her slaughter his entire squad and attack other of his friends. Then again, pretty much all their interactions became this in hindsight, particularly the one where, while sparring, she pinned him to the ground and straddled him, saying she wanted him to learn to talk to girls.
England and France have a long-running bitter rivalry and never pass up an opportunity to fight each other. It doesn't help that France almost succeeded in forcing England to marry him at one point, and also attempted to molest England when he was bedridden.
In a Birz comic, in response to France's flattering, America accuses Russia of being the bad guy considering his good relations with Germany and his tradition of kissing people as a greeting. Russia then scoots over to America, flashes a Slasher Smile, and offers to make his gums bleed (therefore implying that he just offered to roughly kiss him). America doesn't get it. Later on, while England complains about America's provocative attitude, Russia says that he thinks it's one of his better points, before adding that provocative people are fun to snap in half.
The attraction that Slan, the female member of the Godhand, has to Guts. Given that she's a sadistic demonic god, she derives a lot of pleasure from all the suffering she and the other God Hands can put him through. And it's not exactly helped that Slan is Too Kinky to Torture — the only thing Guts succeeds in doing by impaling and blowing off half of Slan's torso with his Arm Cannon during his battle with her in the Qliphoth is giving her an orgasm.
In episode 10 a villainous Elegant Gothic Lolita named Ashley calls her enemy Shusei "handsome", says that he's 'just her type', and takes pleasure in torturing him via a voodoo doll all the while saying he should give up and tell her what she wants to know because she doesn't want to hurt him. She then puts him to sleep and whispers in his ear "I knew you'd make a beautiful corpse. You're part of my collection now. You'll never wake up again" while caressing his face and chest.
For rival crime lords who have attempted to murder one another at least once, Mr. Chang and Ms. Balalaika sure do behave rather flirtatiously towards each other. One scene from the manga has both of them explicitly state that the times they'd tried to kill one another are the most valued experiences that either of them posses.
Rock and Balalaika, particularly during the Tokyo Arc.
The scene where villainous Creepy Child Gretel disarms Eda in Episode 15 has some disturbing erotic overtones. It doesn't help that after the first grope (feeling for her gun holster, so it's justified), she gropes her again, this time lifting up part of tank top and grabs a nice handful of Eda's cleavage while her voice drops an octave.
There is a very twisted straight example in the warped relationship between former 3rd Espada Nel Tu and 5th Espada Nnoitra Jiruga. Nel's constant attempts at saving Nnoitra, coupled with the fact that Nnoitra, no matter what he does, cannot seem to get her out of his head don't help.
Orihime has had quite a bit of subtext going on, mostly with Ulquiorra and Grimmjow, but there's even a little with Aizen too.
Busou Renkin: Papillon's obsession with Kazuki. Magnified by the fact that there's already a lot of subtext around Papillon with his flamboyant outfit including speedos and a distinctive butterfly mask.
Schneider and Wakabayashi from Captain Tsubasa, especially in the Road to 2002 TV series where Schneider has borderline feminine looks and there's a whole episode dedicated to showcase their thoughts on each other. It's like the animators and character designer were Genre Savvy enough to make them not only more bishonen than in manga canon...
Syaoran Li towards Sakura from Cardcaptor Sakura early on. You can just feel the enmity (and the attraction) between those two. Becomes canon later on.
Accelerator towards Touma. Comments such as "You're really the best." and "Interesting, interesting" were thrown around. And then afterward Accel seems to develop a inferiority complex in regards to Touma, and grudgingly looks up to him as a hero.
Fiamma calls Touma the main dish, and part of his plan involves literally taking a part of Touma inside of himself.
Chrono Crusade has Aion/Chrono. In the manga, Aion is really Chrono's twin brother, unknown to him, and actually cares quite a bit for Chrono. The anime adaptation also included a scene where Aion holds Chrono's face in his hands and leans so close while speaking to him that their lips are almost touching. He also has a bit of In Love with Your Carnage for Chrono in both versions.
Suzaku and Lelouch seem to have a... thing for each other. Sure, Lelouch has wanted to marry him off to Nunnally, but that guy has a Big Brother Instinct larger than he is, so he would want what he believes is truly the best candidate for his sister. It doesn't help that Lelouch treats both the whole 'Suzaku selling him to the Emperor' thing as well as the 'apparently selling him to Schneizel' thing later like Suzaku was cheating on him. Surely that whole thing Suzaku had with Euphemia really doesn't count, since R2 episode 21 has Suzaku seemingly getting over it and becoming Emperor Lelouch's Knight of Zero. With a really smug look on his face. After a month of being alone with Lelouch (C.C. was there too, but...)
R2 Episode 25 brought it to a whole new level. Lelouch, still in Suzaku's arms, gently caresses Suzaku's mask while Suzaku tearfully swears to fulfill Lelouch's Last Request.
Kallen and Suzaku, if only because of the her-being-naked when they met on an island in season one and in pseudo-bondage when she's captured by Britannia in R2. In the end Suzaku ends up becoming Zero, who Kallen was pretty much devoted to throughout most of the series. During their last battle, she actually calls him anata. For those not in the know, this is the pronoun used between spouses, among others.
During the later part of R2, Kallen and Lelouch.
Rakshata and Lloyd.
Schneizel and his younger brother Lelouch. Schneizel refers to Lelouch as the man he loves and fears the most.
Spike and Vicious from Cowboy Bebop, especially Vicious who is obsessed with Spike to a decidedly unhealthy degree (not that anything involving Vicious ever approaches healthy).
Dai no Daibouken has the relationship between Marm/Maam and Hyunkel (and also Merle's love for Hyunkel, though it's technically after his Heel-Face Turn). The obsession of Hadlar/Hadler with Aban/Ivan/Avan then Dai teems with subtext. To be fair, few men can admit with so much seriousness and class that another man's fighting technique excites them and that it's become their only reason to live.
Darker Than Black: In the second season, Genma makes some creepy comments about Suou being cute, hits on Yoko, and also declares love for Hei.
In the DarrenShan manga, there is a lot present between Steve and Darren. Steve's descent into evil was shown to pretty much have been caused by a misunderstanding that Darren didn't love him enough. It doesn't help that Steve had no feelings for Annie, but obviously was obsessed with and had a soft spot for Darren (which is shown when he spares Darren quite a few times.) Although it is later revealed that they are actually brothers.
Light and L. They even spend a significant amount of time handcuffed to each other... and then there was that foot massage.
L also has some of this with Misa, the Second Kira. He tells her that he's a big fan of hers, though it's not certain whether he was lying about that, touches her butt while stealing her phone, ties her up "all fetishy" during her interrogation, and later sweet-talks her into helping him catch the Yotsuba Kira. When Misa kisses his cheek, L answers with, "I could actually fall for you." Again, though, this may have been a lie, according to Word of God.
Mello and Near's odd concern about each other. Mello is so overly concerned with everything Near does it comes across as stalkerish. When he talks about Mello, Near is likewise very complimenting and admiring, and toward the end says he and Mello should have been partners, and that it would've led to great things.
Near/Light. From the moment Light first talks to Near he gets the feeling that he's talking to L. Near keeps calling and harassing Light at odd hours of the day and night and hanging up. Near has a habit of making some very unsettling facial expressions when thinking about what he's going to do with Light and in the manga there's how Near wanted to KEEP Light. When Near corners Light it's dripping with rape metaphors.
Beyond Birthday is COMPLETELY obsessed with L to the point he dresses like him and copies his mannerisms and the way L delegates the case to Naomi Misora and given their mysteriousshared history it kind of comes off like he's hiding from his abusive ex-boyfriend. Implied between Naomi and Beyond, especially in the scene when she's working the case with him and she stops and stares at her wedding ring like she's having second thoughts about being engaged to Raye-the plain Betty to B's Veronica.
Quite a bit between Allen and Tyki. Some notable scenes include Tyki "killing" Allen (which resembled a sort of "violation," with Tyki sticking his hand into Allen), the suggestive dialogue with Tyki telling Allen, "Don't be so cold, boy. An Exorcist made a Noah strip down to his underwear. Was that the first time you did it? Do you think it was destiny for it to be us?" and Tyki seeming miffed when Allen tells him that he'd done it to many people before. During their fight later, there's another Does This Remind You of Anything? moment with Tyki telling Allen, "This is giving me the thrills. I'll break you, one more time, with this hand!" Not to mention Road telling Lavi that Tyki likes Allen as much as she does (this being after it was established that she likes Allen enough to kiss him).
Which she does, by the way. And then spends most of the next chapter basically trying to cuddle with him. Face it, Allen is just a Noah magnet.
Some fans also see Allen's constant bickering with Kanda as this. In the recent chapter it seems like it will actually truly be this. Instead of just the simple bickering.
There are serious hints of this between the Millennium Earl and the 14th Noah. In chapter 196, when asked by Johnny why the Millennium Earl is so interested in taking Allen (or rather, the 14th) away with him, the Millennium Earl says "Why.... by his side. I want to be by the 14th's side." And this is after the 14th has publicly expressed his clear intention to kill and replace the Millennium Earl.
Digimon Adventure has a good amount of this between Tai and Matt. Sure, they look like fistfights, but for simple brawls, they sure wind up on top of each other frequently. And then there's Matt's "nothing will ever come between us again" schpiel.
The real gold is Digimon Adventure 02, and not just because Ken starts out as an actual foe. To quote the Dub Text, "Seeing you squirm is so delicious." Not to mention the "And it isn't long now, pretty boy!" comment (ironic, since Ken's far more bishonen).
Daisuke Niwa and Satoshi Hiwatari. Daisuke initially transforms with a picture of Risa; Satoshi transforms with a picture of Daisuke. The climactic arc begins with the two of them cast as romantic leads in a play, and ends with The Punishment pitted against The Power of Friendship. A later chapter had Satoshi stating that he was unable to bring himself to hate Daisuke, despite resigning himself to hating everyone, simply because Daisuke is the way he is. Then he admitted 'that was the only thing that truly ever brought me joy'. It was suspiciously similar to a love confession in other manga, complete with a montage of all of their important moments together (along with a gigantic image of Daisuke smiling) that went on for two pages.
Dark and Satoshi. "You would have been just my type if you were a girl" indeed. And not to mention that one scene where Satoshi was Disguised in Drag and Dark almost kissed him.
Mana Aida alias Cure Heart and Regina. Subverted though, despite being enemies, they started their relationship as friends. But due to some strange events, Regina became more evil than before, though that didn't stop them having an Odd Friendship. But later, Regina underwent a Heel-Face Turn and they were real friends again. They even said "I love you" to each other! Unfortunately, Regina's father King Jikochuu has brainwashed her and Regina is Mana's foe again. And when Regina is finally back, Cure Heart glomps her.
Rikka and Ira. In Episode 4, there was a joke that Ira have been fallen in love with Rikka. Then in Episode 26, Ira gets hit by lightning and suffers a temporarily amnesia. Rikka cures him after she found him. Did I mention, that Rikka is also shipped with the heroine Mana.
In Episode 41, Makoto (who has Mana as her Fangirl, by the way) tells Regina her (platonic) feelings with her song. While Regina is attacking her with a extremely powerful weapon, Makoto still goes on singing while walking to her, transforming into Cure Swordand catching the weapon with one hand at the same time. Then, she touches Regina's face and the song actually affects on her heart, but it isn't enough to break her brainwashed stage. This is interestting, considering how Mana loves both of them.
Vegeta certainly seems to have this level of obsession with the main character Goku. Then again, people always talk about Vegeta's obsession with Goku, but which one of them had a visualization of the other completely nude?
In the Japanese version, when Vegeta is naked and taking a shower, he stares up at the showerhead and says Goku's name.
In a Non-Serial Movie, Vegeta hilariously shouts "Kakarotto Wa Ore No Mono Da!!" when Android 13 is beating his rival to death, and charges in to protect Goku. The context of this sentence is "Kakaroto is MY PREY hands off him", but "Ore No Mono Da" is usually used by jealous ex-boyfriends to say "belongs to me".
Shobu and Hakuoh in Duel Masters. Even within the context of the card game being Serious Business, Shobu's obsession with getting a chance to duel Hakuoh got... well.. pretty weird at times. At one point, Shobu decides to stop playing the game just because he thinks he lost his chance to go through the temple guardians and face Hakuoh, despite there still being tournaments, et cetera, out there. After Hakuoh's Heel-Face Turn, it no longer qualifies, obviously. Given the satirical nature of the English dub, it's odd that this wasn't brought up more in-series.
Shizuo/Vorona, and Namie/Mika. Erika claims to see some between Kadota and Chikage. Kadota is not amused.
Izaya has moments like this with the girls he almost convinces to commit suicide. After one of them breaks into his hospital room and tries to kill him, he hugs her tightly while thanking her and telling her how much he loves her. Of course, it's plain creepy in context.
Kanra and Bakyura spend the majority of their time flaming each other on the chat boards, which Kanra jokes is because Bakyura's just totally Tsundere for her. Now add in the fact that Kanra is Izaya and Bakyura is Kida, and that they both know it...
Mikado and Aoba. As soon as Aoba is introduced in the novel, he instantly latches onto Mikado. Then you realize he's the leader of Blue Squares and simply wants to control Mikado. When it seems like he'll get his wish, Mikado retaliates by stabbing him with a ballpoint pen (thus earning his title as Memetic Badass and telling him that he stabbed him for involving Anri in his little game. Now the two are working together in the merged Dollars/Blue Squares group and Aoba seems to have taken Masomi's place in Mikado's life...almost completely. Add to the fact that Aoba admitting to Izaya that he's a masochist who is still looking for a special someone to be his sadist. Looks like he's found the person.
Izaya simply has this with everyone. Not just the ones mentioned above, but also Earthworm (who was torturing him), Namie, Mikado, Mikage's brother...just everyone.
Akabayashi fell in love with Sayaka, after she handed him his ass and had pierced his right eyeball with her katana, because he was impressed by her swordsmanship.
Eyeshield 21 has this strongest with Shin and Sena. Unlike most shonen rivals, their relationship is completely free of malice, but that just makes their preoccupation with eventually facing each other again seem more like two people in a long distance relationship. When Sena thinks Shin's completely outclassed him, he breaks down in tears at disappointing him.
Fairy Tail: Somehow it's not as creepy as it ought to be to watch Jellal tell Erza he loves her while she screams about what a bastard he is as he tries to sacrifices her to revive the series' equivlent of Voldemort.
In the fourth season's OP, Louise gets licked on her face by a new, evil purple-haired girl named Janette and the girl hugs Louise close to her with a blushing Louise struggling to get away. And in episode two Janette tricks Louise by pretending to be a plebeian, gets close to her face, and licks her again. She also touches her face and says that if things had worked out different they could have been friends. She also calls Louise "cute and innocent".
Wardes tries to marry Louise, and in episode 2 of the fourth season you get the feeling that Joseph was about to rape Louise for a second when he said she was gonna "lose her honor", then you see his robe lowering and how he kneels in front of her while she's tied up on the ground and touches her face...
Season 4, Episode 6, when Henrietta gropes Louise's super flat chest. While they are fighting over Saito. In the middle of a hot spring, buck naked.
Kaze and Kumo in Final Fantasy: Unlimited. In fact, fangirls seem so obsessed with this pairing that this troper, much to his chagrin, struggled to find anyone interested in the actual continuation of the story when he offered to translate it.
Fruits Basket has Yuki and Kyo Sohma. Kyo's *ahem* obsession with Yuki is typically hostile, but he expresses blatant worry at times when Yuki is vulnerable. When Yuki collapses from an asthma attack Kyo abates his fight with Haru to see if he's ok, and when Yuki is confronted by Akito Kyo can be seen watching from afar with a frown on his face. In the English dub of the anime Kyo and Yuki start almost all of their fights by shouting let's do it! and clenching the fronts of each others' shirts. (Kyo and Haru do this once in episode 10 as well.) Best shown when they fight and Yuki got close enough to kiss Kyou before kicking him away. One aspect of the curse renders them unable to hug girls, so who else will they take out their stress on? The whole "naked when you transform back" thing doesn't help. When Tohru attempts to imagine them getting along, picturing them gushing about each other's virtues by a lake complete with Bishie Sparkle.
It always seems like Envy's flirting with Ed whenever he talks to him.
In her battle with Roy, Lust combines flirting with trying to kill him, even as he keeps killing her. At one point, she comments "Didn't anyone tell you it's rude to put your hand between a woman's breasts"- at this time, Roy is setting her on fire (literally), and also literally has his hand inside of her chest, trying to destroy her Philosopher's Stone. As she dies, she makes a comment about kind of appreciating being killed by a man like him.
Pride tries to take over Ed's body as a new container and gives him a lecture. Not to mention Edward defeats Pride by transmuting himself as a Philosopher's Stone and "forcing his way inside" Pride. Note that both Ed and Pride are having an Out-of-Clothes Experience for this scene. He's also kind enough to put his true form on his jacket.
Gauron's one-sided fixation on Sousuke is like this. In episode 24 while Gauron's trying to blow himself and Sousuke up (possibly in his screwed-up mind, as a lover's double suicide), he cries out, "I LOVE YOU, KASHIM!" About Gauron's line "I love you, Kashim!" — in Japanese, Gauron actually says "Aishiteru ze", which literally means "I love you" with all the romantic and sexual connotations attached to it.
Their last encounter during the third season doesn't improve matters. The way he talks you'd think Gauron is expressing disappointment that Sousuke has cheated on him with someone else (which, in his own screwed up way, is exactly what Gauron is implying — just not in an openly romantic fashion). Which is followed by Gauron's screwed-up version of consummating the relationship. In the dub, there's a hint that Gauron's crush might not be so one-sided after all, because the dialogue implies that trying to kill Gauron is just as important a reason for Sousuke to continue living as protecting Kaname.
In the novels, Gauron comes straight out and tells Sousuke that he actually fantasized about killing Sousuke, dragging his corpse out of the AS and fucking it. Gauron was shown to be recording video footage of Sousuke, and was watching it with ecstasy. His partner, annoyed with the results, asks Gauron what exactly Gauron is getting out of this video. Gauron replies gleefully that it's all worth it, since he can watch his "precious boy."
Every single interaction Gauron has with anyone can have rapist vibes to it. In the novels, Kaname finds out that "that creepy, disgusting man" stripped her naked for the experiments, which made her writhe in disgust (coupled with how, later, he calls her "Kana-chan," something only her best friend Kyoko calls her). And then there's his manhandling of Tessa, where he makes it clear that he'll do "X-Rated things unsuitable for minors to see to this cute little captain" if they don't obey. And after she heads off one of his attempts at attacking a submarine, he handcuffs her, pulls her by her hair, gets close to her face, and tells her with that he's "really mad," but that he'll "punish her" instead of killing her. And then there's his way of subduing Dunnigan, which looks a lot like him asserting who's the one in charge by pseudo-raping him (c'mon, look◊at◊ this◊).
Police Woman and Bonta-kun. Seriously.
Lampshaded and teased between Tsubaki and Sousuke, with their rivalry and constant bickering. In the last episode of Full Metal Panic? Fumoffu, when Tsubaki thinks he's going to die, he even tells Sousuke that confessing to the girl he loves isn't as important to him as having one last fight between them. Matters aren't helped when, in one side story of the novels, Tsubaki makes a mistake and accidentally confesses that the one he loves is Sousuke. Afterwards, Kaname is shown to giggle and discuss who would be the submissive "receiver". She says both of them are.
Kurama, Gauron's partner in Amalgam, is shown to have started getting this way towards Sousuke. Although he initially shows annoyance and skepticism at Gauron's obsession and worship of Sousuke, when Kurama himself comes into confrontation with Sousuke, he starts to admire Sousuke more and more. After hearing that Sousuke massacred a bunch of his subordinates, he notes that "Mr. Iron was right. You are a very interesting boy."
Nakago's (canonically one-sided) obsession with Tamahome. Complete with a scene where Nakago licks the blood from Tamahome's cheek (from a wound he inflicted) and tells him "You excite me... not in the same way as a woman, but more like a toy.", and Nakago kissing Tamahome. Granted, he just did it to spite the love between Tamahome and Miaka.
The episode of the parody Fushigi Akugi where Nakago receives a letter from a fan asking him if he's got a crush on Tamahome. He starts seducing Tamahome (who is immediately put off) and says that it must be done for the fans. Cut to Miaka watching the whole... ordeal from the doorway, saying she's "impressed" by Tamahome.
For a while there was also some Yui/Miaka before it turned back into Les Yay.
In Futari wa Pretty Cure, Honoka and Kiriya develop feelings to each other. It hits her hard when he was called back to the Dotsuko Zone where he's apparently killed. Kiriya isn't killed, but due to Jaaku King's defeat, Kiriya dies, too, but it's suggested that he's reincarnated as a normal boy.
Akabane's major goal in life is get his kicks however he can — preferably with a very challenging murder involved somehow. The eponymous duo are his favorite opponents. He seems to go out of his way to work with (or against...) them.
Ban and Shido, who aren't trying to kill each other only because they have a mutual friend.
That time Ban saw Kazuki naked, and their interactions tend to flip between highly suspicious games of "I-know-something-you-don't-want-me-to," childish name-calling, and Teeth-Clenched Teamwork. Also, Kazuki states that he finds Ban very intriguing and early on, seems to be stalking him and Ginji for kicks.
One of the most pronounced and blaring Foe Yay in the series can be found within the Ax-Crazy Fudou and Ban (though it's definitely very one-sided for Fudou). After Ban ripped off Fudou's arm, Fudou becomes completely obsessed with Ban. He even keeps his own severed, rotting arm with him to constantly remind himself of Ban - which made him feel "incredible chills rising up throughout his body." Pretty much every line he spouts to Ban is very homoerotic. And when he isn't talking to Ban, every word coming from his mouth is normally about Ban. Some notable lines include: "COME, COME, COME, COME, your eyes, your flesh, blood, your screams, GIVE YOUR BODY TO ME! MEET MY DESIRES!" "Don't die yet, Mido - I'm not finished. You still need to quench my thirst - I'm not done. Let me enjoy myself." "What was my job again? My mind goes blank whenever I see you." "The only thing that can stop this shaking... is for me to slurp up your blood!" And when Ban starts worrying about his Heterosexual Life Partner Ginji, Fudou gets pissed. "What are you looking at?! Look at me, Takuma Fudou!!"
Though Fudou's death scene was kind of sweet... in a weird, warped way. He confesses to Ban that he's happiest when he's fighting him, and that he wishes that they could go on like this forever and ever. And Ban, on the other hand, ended up using up his Evil Eye so that Fudou could have a nice dream before he died, of them continuing to fight. Ban's expression when he gently closed Fudou's eyes was actually pretty emotional and filled with compassion.
Hijikata and Gintoki, being complete rivals in everything from swordfighting to favorite foods. Sunrise gleefully lampshades certain aspects of their relationship in the anime. For example: At one point in episode 92 we see Gintoki holding a mock manga cover with him and Hijikata in a suggestive pose.
Okita and Kagura have this in spades. She doesn't seem to like Okita much, but she can feel this kind of vibe coming off of him towards her, and they get along fairly well when they're not fighting.
Kamui got excited watching Gintoki fight Hosen and later declared Gintoki is his (prey) and that he won't allow anyone else to touch him.
This defines the relationship between Rally Vincent and the Big Bad Goldie Musou, even though it's decidedly one-sided, with Goldie's desire to possess Rally, body and soul is the main reason for their conflict.
To a lesser degree, the relationship between Goldie and Rally's junior sidekick Misty Brown. In one scene Misty drugged senseless in her underwear, in the next Misty in leather bondage gear, crying. And in the last book of the series the two end up in a consensual relationship! Seriously!
Guilty Crown's first bit of foe yay is rather unsettling in that the one going yay is a thirty-to-fourty year old Axe CrazyTorture Technician and the one he's yaying about is a seventeen-year-old school boy. Hihg-ranking GHQ member, Makoto Waltz Segai, actually shoots a sniper that's working for him in order to see young Shu use his powers. Two episodes later, he thinks back to that moment and says that he feels like he's falling in love. Considering the writers and the director, there may be more of this coming.
Alucard and Father Anderson. "My beloved enemy!" "I could have given you my heart..." "Someday, we'll meet in Hell."
Major flirts with Integra quite a bit, even shutting up anyone who interrupts his conversation with her in volume 4. Not to mention: his desire to have her at his side while he defeats Alucard, because this is a show he has to behold next to a beautiful woman.
Anderson and Integra in volume 6, rescuing her and escorting her home.
Rip van Winkle and Alucard, and their notorious "fight" which is presented in all versions as almost exactly like a rape scene.
Alucard and Major. They're both fascinated with each other and when they spoke to one other after 50 years, they spoke like they were old friends.
Zorin Blitz and Seras. Zorin calls Seras pretty while mutilating her and appears to have a particular fascination with maiming her.
In Alucard's battle with Alhambra he hooks both of his thumbs into his mouth and he looks at him rather...wistfully. And then bites his neck.
High School D×D, one-sided between Issei the protagonist, and Vali his rival, more on his side. Issei just doesn't want to do anything with him while Vali would like to defeat him. The latter stated that he looked so uncool in front of Issei when Cao Cao used Samael, the dragon eater, to poison him.
Touya Akira and his rival Shindou Hikaru spend 95% of both the manga and the anime Hikaru no Go obsessing about each other — hell, Hikaru even learns to play go because he wants Touya to be obsessed with him and not Sai. Naturally, the yaoi doujinshi and fanfics starring the two of them are legion.
Higurashi: When They Cry - Tomitake and Takano in Minagoroshi-hen. Keiichi and Rena in Tsumihoroboshi-hen's rooftop battle scene, and maybe Onikakushi-hen. While not foes in most arcs, Mion and her twin sister Shion, especially in Meakashi-hen and Wataganashi-hen.
Hisoka, especially in the manga, has been shown numerous times to get a hard on when he sees Gon and Killua (though one could argue that that happens most often with Gon). He felt that they have great potential to become amazing fighters and desires for them to become strong enough to offer him a truly satisfying duel, and he plans to kill them when they become "ripe". However, in order to allow them to reach this stage, he refuses to let them die, demanding that their death be through his hands alone and when Illumi was ready to kill Gon, he thinks that he can apologize to Hisoka later despite Hisoka having said that anyone who tries to kill Gon "will not be let off lightly." He even teamed up with the pair against Razor. It's especially obvious in episode 5 of the 2011 remake anime where Hisoka becomes quite excited and blushes when fighting Gon.
Hisoka also has some towards Kuroro. And towards Kurapika; during the fourth stage of the Hunter Exam, on Zevil Island, Hisoka refers to him as an "unripe fruit", however, his interest in him is minimal compared to his interest in Gon and Killua. At some instances he referred to Kurapika's blue eyes as "delicious" and Kurapika's scarlet eyes "exciting". He forms a loose alliance with Kurapika later, however, against the Phantom Troupe.
Perhaps Sesshoumaru is just after the sword (in a manner of speaking) but he and Inuyasha who are brothers, tend to have quite a bit of Foe Yay happening between them — especially in the earlier parts of the series. Arguably, this continues into the third movie.
Kikyo and Naraku. The mutual sexual tension between the two is evident. Near the end of the manga, Naraku admits that he really wishes Kikyo's love.
Jakotsu and his enemy Inuyasha, which is very one-sided on Jakotsu's part towards Inuyasha. He also flirts with Sesshoumaru and Miroku once.
Kagome and Naraku near the end of the series.
Half of Naraku's lines (especially during combat) could easily be misconstrued, as he has a tendency to nab the male Youkai main characters in his tentacles, then declare things line "And now you will become one with my flesh!".
In Part 2, Wham tries to ensure that Joseph will fight him when he gets stronger... by placing a poisoned wedding ring inside of his chest that only he has the antidote to.
Part 1 ends with Dio acting upon his desire for Jonathan's body, and his plan to use it to "live gorgeously forever." The last bit of the scene is quite emotional, and suggests Dio cares for Jonathan beyond simply wanting to graft his severed head onto Jonathan's body. Had they but world enough, and time.
Part 3 ramps it up with Dio constantly caressing Jonathan Joestar's birthmark. And his Fabulous Gay Harem escapees, Polnareff and Kakyouin. And Abdul verbatim describing Dio as 'weirdly sexy.' Real kicker is when Dio goes into a fit of laughing glee that resembles nothing less than a prolonged evilgasm after using Grandpa Joseph as a mystic slurpee.
Jyu-Oh-Sei: Thor/Zagi, and to some extent Thor/Third as well.
Kara no Kyoukai: Lio Shirazumi not only lusts after Shiki, but seems to feel this way about Mikiya as well.
Karneval has Akari and Hirato's relationship, though it's mostly one-sided and amusing when they're not being serious.
Katanagatari has some of this between Emonzaemon and Houou and with Togame and Princess Hitei.
Kemono no Souja Erin: Damiya becomes suddenly very touchy-feely with Erin, when it turns out that she can control the beast lords. During their first meeting one-on-one he grabs her hand, gets very close with her and compliments her eyes. Unsurprisingly, when they are interrupted by his aunt, she assumes that he tries to force himself on her. He also seems to be impressed, when Erin doesn’t buy his sweet talk and is overly fascinated by her ability, even comparing her to Je, when she rides on Lilan to rescue the queen.
From the same series, we have Harime Nui, whom spends half of her screen time insinuating to both Satsuki and Ryuko that they are cute and that they actually love her. This is due to her view that love and hate are two sides of the same coin.
Kimba the White Lion: Claw has a one-sided case when it comes to his obsession towards defeating Kimba.
Soubi with two of the main villains. One being Ritsu-sensei in which they actually were sort of in a relationship. (Ritsu took his ears) and Soubi was upset when Ritsu gave him to Semei. But currently they're both just sort of neutral to each other now. And, of course, Semei. With Soubi's obsession to obey the man's every word, despite how he purposefully abandoned him. And replaced him with his real Beloved fighter Nisei. However, Soubi's obsession could be because of the way he was trained and nothing more.
Ritsuka and Semei. Though Semei doesn't see Ritsuka as his enemy, Ritsuka is kind of torn on what Semei is, exactly, due to what people have told him about him and many unanswered questions. Such as why he faked his death.
Tsukuyomi has a huge obsession with her Setsuna. She's a fairly minor villain, but when she shows up... holy crap. The next chapter turns it up to 11, with Tsukuyomi first hitting Setsuna with a Clothing Damage spell, followed by pinning her on the ground, and slowly and deliberately cutting off Setsuna's sarashi bra. After Fate calls a retreat, she says "Just looking back on this match will give me more than enough fuel for my fantasies." Take from that what you will.
And at the end of chapter 304 Tsukuyomi and Setsuna meet up again. Tsukuyomi powers up and tells Setsuna "This is so that I can savour you to the fullest, sempai! Now, allow me to feast upon you...to the very core!"
Fate has an odd penchant for literally getting in Negi's face at times and invading his personal space. And when he appeared to be quite entertained and had a smile on his face, in contrast with his normal stoic expression, during one of their fights together when he saw that Negi had gotten stronger: "Beautiful. That's what I'm looking for Negi-kun." In chapter 318, it's Negi who turns the tables and gets in Fate's face.
In chapter 290 Tsukuyomi suggests that she will fight Negi herself. And Fate, known for being quite the Stoic, actually gets pissed and firmly states to Tsukuyomi "His opponent shall be me." At the end of the chapter Fate thinks: "I am a tool. Nothing more than a mere doll that exists to bring my master's dream to fruition. But Tsukuyomi-san, there may indeed be some truth in what you say. Negi-kun...right now, you alone...to do battle with you is my one true desire!" (The caption at the end reads "Primal desire from one without a heart.") Tsukuyomi mentions his infatuation with Negi as the beginning of his own identity.
In the next chapter Negi conquered his inner demon by deciding that he wants to defeat and befriend Fate.
In chapter 293, Tsukuyomi has a typically weird and disturbing moment when she gets all gooey over Negi's new level in badass, and it resembles nothing so much as somebody catching themself fantasizing about a friend's significant other.
In 319, Fate is showing a constant grin as he fights Negi and notes that fighting Negi is his one true desire. Their ultimate fight sureinvolvesawholelotofhand-holding! (Because they basically doing a super magic-powered version of arm-wrestling, but still.) Fate's almost tsundere response afterwards certainly doesn't help. "Don't misunderstand me. I'll help you, but it's not like we're friends, or anything!"
The girls are rather hilariously convinced that Fate is the biggest obstacle in their way to spending time with Negi. Correctly convinced. In the next chapter, when Evangeline lists the two people currently next to Negi, Asuna and Fate, when she talks to Chachamaru about spending more time (romantically) with Negi, she mentions that Fate isn't the type to "do anything" and that Asuna is too much of an idiot to take advantage. She's treating both of them like love rivals.
Kurt Godel/Negi, before Kurt switched over to the good side. One chapter has him pinning Negi to the ground with his leg and leaning over him with a smirk on his face while giving him a We Can Rule Together speech.
Kurt: " I see... So this is the Gospel of Darkness... hahah. Negi-kun... the more I observe you, the more I want you for my own."
Chapter 290 gives us hints of Tsukuyomi/Fate. "Right now, you look awfully worth slicing to me" indeed.
If Mai and Mikoto are the poster children for the series' Les Yay, then surely Natsuki and Nao have to be their Foe Yay counterparts. Seeing the two of them tied up together (but not to each other) and singing karaoke on stage in goofy costumes together may have something to do with it.
There is a Ship Tease moment on one of the Mai-Otome Drama Tracks when Nao joins Natsuki in the shower and confesses that she's only been so harsh and insulting towards Natsuki in order to hide her real feelings. Whether or not she was just lying to gain information is up to debate.
Natsuki has plenty of this with Mai in the manga. For all the fighting she and Mai do over their "key" (male main character Yuuichi Tate), Natsuki spends a lot of time making fun of Mai's figure.
In Mao-chan, it's not even subtext—the supposed-to-be-a-villain Yuriko is very much in love with her diminutive enemy Mao, and doesn't even really want to be a villain (leaving her second-in-command to do all the work.) Mao admires Yuriko too, (probably not that way, but as a Cool Big Sis), although it should be noted that Mao doesn't know that Yuriko is one of the aliens she's fighting.
MÄR has Alviss and the Phantom, which also overlaps with Ho Yay, as the Phantom even attempts to kiss him twice. Alviss spends so much time hating Phantom that during the ghost chess arc he accepts to live together with Phantom for eternity. To be fair, it was more or less mind control.
Mobile Suit Gundam ZZ. Haman Karn develops an obsession with protagonist Judau Ashta after initially mistaking his Newtype resonance for that of Char Aznable, and consequently makes several advances towards him in the numerous encounters they have over the course of the series. The issue regarding Judau's age has led some to believe that Haman's history with Char may have had an influence on her preferences.
One could make a good case for everyone in the series being in love with Johan without anyone batting an eyelid, and Lunge/Tenma is especially pronounced, not surprising due to the similarities between them and Les Misérables.
Tenma/Johan too. What with Johan addressing a letter to Tenma with "My dear Dr. Tenma", and calling him "my favorite doctor"...He basically becomes obsessed with Tenma after he saves his life, and when he is presented with the chance to kill Tenma, he tells Tenma that he could never kill the man who saved his life.
Muhyo And Roji has Muhyo and Enchu, which is arguably halfway canon, what with Enchu's little love confession before getting shut away forever.
Nabari No Ou: Miharu and Yoite start out like this, but are really, really bad at acting like foes, and it quickly blossoms into full-fledged Ho Yay, especially after Miharu's Face-Heel Turn. There's some between Kumohira and Yukimi too. Not to mention the rather creepy scene where Hattori is practically hitting on Yoite - "You really are diligent and smart... as well as beautiful."
Shinji and Kaworu. The sleepover, the bathing scene; Kaworu tells Shinji that he loves him. They're more Ho Yay in the anime and Foe Yay in the manga however, at least on Kaworu's side.
Asuka/Rei could be argued as an example as well, given Asuka's tendency to express romantic interest through outright hostility.
Nightmare Inspector, between Tsukishiro and Azusa. Even before they meet, Tsukishiro hears about Azusa and comments that he'd like to meet him, as he sounds much more interesting than Hiruko. Then in the last few chapters, they finally meet. Azusa threatens to eat Tsukishiro in order to aquire all the nightmares he's eaten. Tsukishiro responds to this by blushing, and giving Azusa a rather flirtatious-seeming look. Later on, he gets trapped in a void in the Delirium, which makes his feelings materialize in a sort of hallucination. In said delusion, he's being stabbed and ripped apart by Azusa, and he more or less admits that he was turned on by the earlier threats.
Noir: Lady Silvana, aka the Intoccabile, gives Mireille an excessively long (and open-mouthed) Kiss of Death. And beforehand, when they were children, she was very obsessed with Mireille, traumatizing her for life. Her behavior did not seem to be so much of an obsession with Mireille herself, as much as an obsession with domination and control. The kiss seemed to be more about putting fear into Mireille by confusing her and establishing dominance.
In Nora, the hatred that the eponymous hellhound holds for Kazuma, combined with Kazuma's constant smirking and remarks of "Interesting..." regarding Nora, make for ungodly amounts of Foe Yay even at their first meeting.
Tabool in Now and Then, Here and There is unhealthily obsessed with garnering any attention whatsoever from his best-friend-turned-rival, Nabuca, to the point that he gets jealous of a freaking six-year-old. Long story short: Nabuca continues to reject Tabool and it does not end well.
Although it was very shortly before she got Put on a Bus, and the author is prone to launch Air To Sea Missiles, the battle between Usopp and Perona seemed this way, at least from her side. Turning giant and giving him a skirt shot... phasing through his crotch... is there any other way to take that?
Zoro and Sanji, who despite being on the same sides seem to loathe each other... yet while Sanji is a complete womanizer, he will drop his fawning over the women in a heartbeat to fight with Zoro, if he makes the tiniest of statements. The filler episodes tend to make fun of this pairing, giving fans two instances in which Sanji and Zoro are almost forced to kiss (once when they were sleeping next to each other, and Sanji had a dream about Nami, and the other when they were hit with Foxy's slow beam and almost drifted together).
Zoro has one with Tashigi, his self-declared rival from the marines. After a short fight he spares her (to her fury), because she reminds him of a childhood rival (with whom Zoro also seemed to have a foe yay).
Nami and Kalifa were very Foe Yay-ish. At one point, Nami admires how smooth Kalifa's skin must be and how she would want her to be her own Sexy Secretary. Lampshaded when she reminds herself that she isn't a Dirty Old Man.
This scene from the anime features Lotti getting close to Oz, touching and licking his face and then putting his face in her boobs. She initiates the Marshmallow Hellin the manga too. In the manga she also calls him "cute". Also, this scene. And this scene where she gets close to Oz's face and intertwines her fingers with his. She also generally disregards his personal space.
In Peacemaker Kurogane (especially in the manga), Suzu becomes obsessed with Tetsunosuke, constantly having his every action monitored. He becomes jealous and scared when Ryoma decides to take Tetsunosuke away with him, taking drastic action to kill Ryoma and frame Tetsunosuke for it, so that Tetsunosuke won't be able to get away from him. Suzu pretty much even comes out and says, after another character asks him why he hates and obsesses over Tetsunosuke so much, that "this isn't hate — it's love."
Peach Girl: Momo and Sae have this for a bit before they become close friends. Then it turns into Les Yay.
Rook and Kaito. The two were childhood friends. Unfortunately, Rook was taken away as a child and eventually became a Tyke Bomb who determined that Kaito was the perfect candidate for Phi Brain. As Kaito solves puzzles, Rook gushes over how beautiful he is when doing so, and concocts a plan to convince Kaito that the best thing to do is to leave his True Companions behind and join him. He gets very angry when Kaito's Love Interest, Nonoha, displays how close she and Kaito are. When Kaito finally makes it clear that he will never join the conglomerate Rook works for, Rook goes into a mad rage, screaming that Kaito is his and that he has to join him.
Between Gammon and Elena.
In Please Save My Earth Gyokuran and Shion are friends but also enemies. Shion is fixated on outdoing Gyokuran in everything he pursues to the point of hurting innocents in his plans, Gyokuran is always fixated on Shion to a lesser degree as well. The animosity outweighs the friendship which only comes through as one-sided from Gyokuran or in dire situations.
The Prince of Tennis. Holy mother of God. Just watch Tezuka vs. Atobe, the Tezuka vs. Fuji and Tachibana vs. Chitose matches in the anime (and both the first and the third matches' original renditions in the manga), both of them full of subtext. And if we go for teammates who are also rivals, aside of Tezuka and Fuji, look no further than Kaidoh and Momoshiro...
Ranma and Ryoga. In the manga, after Ranma defeats Ryoga in a particularly fierce battle, he carries the unconscious Ryoga off the battlefield, Ryoga slumped in Ranma's arms practically straight off a romance novel cover. It's more blatant in the anime, where Ryoga saves female-Ranma from a seemingly invincible snow golem, cradling her in his arms. Ranma uses his (her?) female form often to embarrass Ryoga (and the latter always falls for it).
Parodied by the author in the "Fishing Rod of Love" story. Ryoga is depicted as being absolutely disgusted when he accidentally hits Ranma with the titular Love Potion, and even carries him/her away into the woods with the intent of killing the Gender Bender and burying him/her so he won't have to put up with it any more. When he initially can't bring himself to kill someone so brainwashed that they're perfectly willing to die if that's what he wants, Ranma proceeds to kiss him... and Ryoga's restraint flies out the window and he starts trying to kill Ranma. At the episode's end, Ranma gets freed from the Love Potion and Ryoga accidentally Glomps him while trying to hug Akane... Ranma promptly goes ballistic and beats Ryoga to a pulp.
In episode 87 when Ryoga falls on top of Ranma in the path of an oncoming train Ranma tries to get Ryoga off of him and all the movement makes it look like they're having sex. He also worries about Ryoga when he gets injured and carries him.
The numerous minor male villains that fall for Akane.
Revolutionary Girl Utena: Utena and Akio. They have sex for one and make out for two and Akio wants her to be his princess but is the villain of the work.
Between Alone/Hades and Pegasus Tenma, past chapter 212 (because if chapter 214 isn't a confession, what is?)
Pegasus Seiya and Hades. All started with Seiya's compliment in the middle of battle What are those beautiful eyes! I can't believe these eyes belong to feared Hades, the King of Underworld. They have the depth of a very deep lake. And Stoic Hades snapped when he just realized he knew Seiya since LOOOOOOOONG time ago, and an enraged Seiya dared to reincarnate himself again and again. The irony is when you should take this statement as The Only One Allowed to Defeat You... Hades seems to believe Seiya did this not to protect Athena and human race but to come and wound him. He made it sounds like Seiya or Pegasus saints was obsessed of him after he wound Hades once in the age of myth.]]
InSamurai 7, Ukyo had a fetish for Kirara, who aids the samurai who oppose him. Even though they are enemies, he still wants her in his harem.
Hisa and Mihoko of Saki. Seems like Hisa left quite a large impression on Mihoko after the latter's powers proved quite ineffective against the former.
Mihoko: Maybe she'll tell me my right eye is pretty once again.
Christopher Armalite and Shannon Casull from Scrapped Princess, at least in the novels. In the volume Song of the Forgiven, Christopher becomes inordinately obsessed with Shannon after losing to him in combat. It bothers him so much that he has an entire internal monologue about the nature of his feelings - specifically, whether they're love or hate. The anime omitted this scene.
It's a joke among s-CRY-ed fans that Kazuma and Ryuho really do pound on each other for this reason, since neither seems to have any way to express their respect for each other.
Shakugan no Shana gives us some nice moments between Yuji and Hecate, especially when he was filling her with his existence. It doesn't help in Season 2 that Yuji becomes close to a fragment of her existence posing as a human, and that said fragment has an obvious crush on him.
Tao Ren/Tao Lian/Tao Len of Shaman King spends the first arc of the series obsessing over the protagonist Asakura Yoh and Yoh's spirit partner Amidamaru, furious that he Can't Catch Up with them. Yoh spends this same arc greeting Ren cheerfully whenever they cross paths. When Ren finally calms down a bit and becomes Yoh's Lancer, they arguably act more like an old married couple than Yoh and his arranged fiance.
Shin Angyo Onshi: Aji Tae's attitudes towards Munsu come across as advances sometimes.
Lina lampshades this with Gourry's rival in the first season, Zanguluz.
Lina herself and Martina in the second season, particularly in episode 16, in which they compete in a tennis-like game...did we mention that Martina is confirmed to be named after a famous lesbian tennis player?
Filia and Xellos — he teased her and she tried to punch or blast him all the time. She was visibly surprised at the Mazoku's protective gestures, though.
In one episode of Sonic X, during a fighting tournament, Rouge fights Tails and beats him... by kissing him, and flirts and in one option kisses Tails again in Sonic Battle. A few episodes earlier, she essentially flirts with Knuckles. The latter relationship is canon.
Medusa openly admitted to loving Stein, and Stein has rather obsessively hallucinated about her.
Memetic MolesterNoah gets this with Liz, who he had complemented as almost beautiful enough to collect on sheer looks and knows would do anything for Kid or Patti, and Kid, who he kidnapped. CHAPTER 63 does not help anything.
Gopher/Kid is another squicky possibility. Mutual hatred, one-sided violence due to Kid being chained up. Kid just hangs there and largely ignores both the insults and the beatings, but Gopher sure is putting a lot of effort into hating the shinigami...
Good Lord, do Akagi and Uozumi have this in Slam Dunk. It's been mentioned that Uozumi talks about defeating Akagi everyday and from what we've seen, this is probably not an exaggeration. He almost instantly took an interest in Akagi when he first saw him, cheered him on during the Kainan game, and his rivalry with him is his main motivation for improving. Even after quitting basketball he still travels all the way to Hiroshima just to see Akagi play and even gives him advice in the middle of a game. On Akagi's side he considers Uozumi the better player (despite what everyone else says) and has a great deal of respect for him. Their bromance is even mocked at times, such as when they hug and cry on each other's shoulder, only to show that they're both far too ugly for this to be anything but fan disservice.
Ayeka and Ryoko from Tenchi Muyo! Depending on which Alternate Continuity you choose, they are old childhood acquaintances or mortal enemies, but they always fight — and not just over Tenchi's affections. In at least one alternate world glimpsed during an Alternate Universe episode of the television series, though, they are clearly in a relationship with each other. Though outside forces were involved.
Kamina and Viral. Especially in the Viral's Sweet Dream special (guess who the subject of the sweet dream in question is).
After Kamina's Death, Simon ends up becoming the object of his...obsession. There was one scene in particular, which had the two brawling in the prison wash room, wearing nothing but very tiny towels around their waists.
The No Yay-tastic scene near the end of Lagann-hen, in which a naked Nia is straddled by the Anti-Spiral King as it disintegrates her.
Togainu no Chi: Shiki x Akira. Shiki seems to think everyone except Akira is just "trash", has said that Akira has intriguing eyes, and generally disregards his personal space when he's trying to kill/fight him. Bonus in that it's a canon pairing in the game.
Trigun: Vash and his Evil Twin Knives. Also, in the magazine version of the Tri Max manga, Legato telling Vash that he is beautiful. After beating him to a bloody pulp. Also, Legato is very obsessed with Knives and is so jealous of Vash (or rather, of Knives's twisted love for Vash) and obsessed with killing him that Vash is the only one who manages to break his composure.
Beatrice and Battler. In the anime at least, nearly all their interaction comes off as that of an off-kilter married couple who thinks that vicious arguments are the best kind of foreplay. "The Stakes' Valentine's Day" and the sequel Beatrice's White Day takes this even further and plays it for laughs. As of EP6, it's canon.
Bernkastel and Lambadadelta. Canon, and they were on the same side all along.
Erika and Battler. EP6 has her fantasize about marrying him... and making him surrender to her, and was about five minutes from becoming reality.
Awkwardly sluggish Katayama and vicious bully Tsumura in Uzumaki when they morph into giant snails and are later isolated in a cage. Considering they are the only two giant snails in town (at the moment) and snails are hermaphrodites...
In Vampire Knight, Zero Kiryuu and Kaname Kuran display this trope very well, what with their interactions. Zero occasionally having to drink (blood) from him doesn't help (and, I'm sure, feeds the fangirls). They happen to be the top yaoi couple to be shipped in the fandom. Manga Chapter 82 added fuel to the fire, what with Kaname and Zero's faces ending up very close to each other and Kaname murmuring "Kiryuu-kun...it's enough, right?"
Vassalord: Barry to Rayflo. And only Barry to Rayflo. Not the other way around.
Nitori and Doi from Wandering Son. It's implied that Doi has some sort of attraction to Nitori, and the two are on less-than-friendly terms. Takatsuki and Chiba turned into this early on, but have since gone back to being friends.
From Witchblade, Reiji Takayama and Wadou. Much more true on Wadou's end, but both men have worked their asses off outsmarting each other (Takayama winning almost all of the time), and Wadou looks like he's in the throes of orgasm when he finally appears to have pwned Takayama royally at one point. It later comes back to haunt him in a totally humiliating fashion.
Wolf Guy - Wolfen Crest has Big Bad Haguro Dou, who becomes completely and crazily obsessed with protagonist (and werewolf) Inugami. He initially doesn't care about or even think twice about Inugami... until he pushes Inugami too far. Which results in Inugami showing him his true form and scaring the shit out of Haguro. Haguro goes insane from it, and obsesses and stalks Inugami after that, even cutting himself all over his arm and carving the word "Inu" onto his hand. It's creepy to the point of being something of a sexual obsession as well - Haguro has been shown after that to, while having sex with his (equally crazy) girlfriend Ryuuko (who, by the way, also lusts after Inugami and thinks about him while having sex with Haguro), think only about Inugami, and pretty much screams his name while imagining him. Later, Haguro ends up raping his male subordinate to death, while again thinking of Inugami. And after Inugami decides he's had enough of this shit and tries to move away, Haguro, being the stalker he is, tries desperately to do stuff to piss Inugami off so that he'll come back. He pretty much reached that epitome when he sliced off some of Inugami's fingers, ATE THEM, and then got a fucking boner off of it.
The blood-licking also appears in X1999 between Fuuma and Kamui. Of course, it's CLAMP...
Yugi/Kaiba is really overt in Season Zero. Kaiba stalks Yugi for an entire episode because he suspects someone else is trying to defeat Yugi in a card game. (He interrupts said card game when it looks like Yugi's about to lose, beats the other duelists, and before parting reminds Yugi that he is The Only One Allowed to Defeat You). And in a later episode, Yugi gets hit by a car owned by Kaiba corp. He's fine (...somehow), but the person inside the car needs to be hospitalized. Yugi goes with said person to the hospital, where Kaiba eventually shows up. Upon seeing Yugi and realizing he was the one who caused the accident, Kaiba remarks thusly:
Looks like we really are connected by the thread of destiny. Try to cut it, but it cannot be broken... A thread that entangles us.
Kaiba and Joey. The infamous line from the prelude to their first duel ("Nice grip. Let me show you mine."). Joey's...interesting dream immediately following said duel. The ENDLESS slightly (ahem...very...) insulting pet names. ("Mutt," anyone?). The whole "master-pet relationship" thing.
Kaiba gets this a lot from just about everyone. His duel with Ishizu is a rare male/female example, with her insitence on bludgeoning him until he accepts his past lives.
For all that it makes fun of Yaoi Fangirls, there's Joey/Kaiba foe yay in Yu-Gi-Oh! The Abridged Series as well. ("Oh, Kaiba, your dragon is so big...!") And that's not even mentioning Marik and Bakura, who are the page quote for Foe Yay/Anime right now and are only really subtextual to the extent that Marik keeps holding onto the last remaining shards of his Transparent Closet.
Yusuke and whatever Big Bad he has to fight for that arc. Both Genkai (in Japanese) and Itsuki (in the US dub), being the canonical love interests (former in Genkai's case), make wry commentary about the Subtext Yusuke has with Younger Toguro and Sensui, respectively.
The Karasu/Kurama fight. Whooboy. "I love you; therefore I will kill you"?
Karasu spends the last parts of the Dark Tournament coming on to Kurama; "Your hair is a bit...damaged Kurama...Human bodies are so frail...I know you fear what my touch could do to you...and yet maybe you also want to know it." All this while stroking his hair from behind.
Ayanami and Teito from 07-Ghost. It's especially evident in the minidrama "Escape," where Ayanami is featured crossing paths with Teito and Frau, "making a serious love call" (as Frau jealously puts it), and declaring how he and Teito "cannot live without the other" after a process of quiz show fanfare.