Draco: Yeah, like I'm really going to tell you, because it's your business, Potter. You'd better hurry up, they'll be waiting for the Chosen Captain — the Boy Who Scored — whatever they call you these days.
Harry Potter:Rowling has stated that Albus Dumbledore was in love with Gellert Grindelwald. And even before that, there was... well, lots of subtext in Deathly Hallows to make a reasonably good case for it. Plum velvet suit, anyone?
Draco and Harry's... preoccupation with each other. After being rejected by him, Draco spends their first year trying to thwart Harry, and apparently complained about him through the entire summer break, and in their second year he's so busy teasing Harry that he completely misses the Snitch and loses his first game. Moreover, he's always doing things to get his attention in the Great Hall, even though the Slytherin and Gryffindor tables are on opposite sides and have the two other houses between them. It escalates later, with Harry becoming fixated on Draco and his activities; it's not an exaggeration to say he pretty much stalked him the whole year.
According to Draco's article on Pottermore, the Malfoys were among the few who believed that Harry survived because he was destined to become the next Dark Lord. When Harry refused his friendship, Draco knew right away that wasn't the case.
Apparently, Draco has been frustrated for over seven years, because he teased and bullied Harry at every opportunity he got, since their first encounter. He was so deranged by Harry's refusal, that he became his greatest rival. Too many issues, Draco?
Please note that in HBP, Harry thought of Tom Riddle as handsome seven times. Dumbledore, by contrast, only referred to Riddle as handsome once. By the transitive property of Foe Yay, that makes Harry seven times gayer.
Except that we're not in Dumbledore's head, of course.
And if Tom seems to have vague echoes of Grindelwald about him...
And Harry also thinks of Grindelwald as handsome multiple times.
James Potter and Lily Evans, in their schooldays, until James matured and deflated his head a bit, and they started dating. Fanon assumption, and hints within canon, say that they evolved into Belligerent Sexual Tension before finally getting together.
Christopher Paolini's Inheritance Cycle has a few truckloads of this. Eragon and Murtagh are two frontrunners. There actually is a rather overt canon example of this trope in the books (though it is dealt with the most in Inheritance) - but it's with Murtagh and Nasuada, not Murtagh and Eragon. Scream in horror, Yaoi Fangirls.
It's a lot easier to infer these kinds of relationships with older works, where it can be argued that motives were "purer" and obsessions were stronger (more importantly, slash fic hadn't been invented yet so authors didn't check themselves for subtext). Case in point? If Les Misérables had been created in modern times, Javert/Valjean fic would bury the internet. As it is, it's definitely one of the most popular pairings in the fandom.
Actual quote from the book itself, about Javert:
A score of times he had been tempted to fling himself upon Jean Valjean, to seize him and devour him, that is to say, to arrest him.
Well the French do call it the little death, and arrest can mean death...
Or this gem:
Jean Valjean, in fact, took possession of Javert by sitting down on the end of the table. He caught up the pistol, and a slight click announced that he had cocked it.
What comes next: "Jean Valjean took Javert by the martingale, as one would take a beast of burden by the breast-band, and, dragging the latter after him, emerged from the wine-shop slowly, because Javert, with his impeded limbs, could take only very short steps. Jean Valjean had the pistol in his hand."
Parodied (or else possibly played straight in a Crosses the Line Twice fashion) in Tales of MU, where Mackenzie can barely think of the bitchy fox girl Sooni without having a long Fetish Fuel-ed fantasy about her. This came to a bit of a climax when they actually got into a fight.
Mackenzie: Sooni, we're not rivals. And we're never going to be friends. I'm not like your nekos. I'm not somebody you can push around and then expect them to just turn around and worship at your feet, or kiss your ass.. or lick your pussy while you call me filth, or whatever it is you want me to do for you. Sooni: [joyously] Subtext! See? We have subtext now! Lynette: I'm not sure that qualifies as 'sub' anything.
Dracula/Jonathan. Their love is so unspeakable, Harker can barely bring himself to talk about it. Literary scholars debate whether this was intentional or not, but they almost all agree that Dracula was intended to have Foe Yay with Mina and Lucy, and that the female vampires were to have Foe Yay with everyone in sight. Stoker was a rather old-fashioned type writing when social and sexual liberation were taking off, so Evil Is Sexy took on a whole new meaning as an Anvilicious appeal for restraint. (Scholars also note that while Dracula is knifed, female vampires are all killed by having something long and hard stuck in them. This is discussed in SERIOUS SCHOLARLY WORKS.)
Not intentional? Come on. When his wives are coming after Jonathan, Drac shows up and chases them off, saying, "He belongs to me!"
In The Seven Realms, Han is a sixteen-year-old boy born on the streets that, by chance, stumbles upon the Bayar family's evil plot to take over the Fells. He's also a supreme Chick Magnet that boarders on Memetic Sex God status. His good looks do not go unnoticed by Fiona Bayar, the daughter of the Bayar family, who initially behaves somewhat similarly to a Tsundere before becoming a Clingy Jealous Girl, getting into an angry argument with another girl that seemed to be getting close to him. By book three, she's openly attempting to seduce him, saying things along the line of We Can Rule Together.
Not to mention how at the end of the book, Hawthorne refers to their relationship as hatred "transmuted into golden love."
Not to mention how Chillingworth fondles Dimmesdale's chest while the latter is asleep. This isn't even getting into how much more Foe Yay there is if you take every instance of the word "intercourse" in a different way than Hawthorne intended.
The V. C. Andrews miniseries have this as part of the formula. Every miniseries, two of the girls will barely be able to stand each other, be complete opposites, snap sarcastically at each other, and have ridiculous amounts sexual tension. Crystal and Raven in Orphans, Jade and Star in Wildflowers, Teal and Robin in Broken Wings. It's hard to distinguish between this and straight Ho Yay...
Edward and Jacob from Twilight. Especially after the charade in Breaking Dawn, with Bella getting pregnant and Edward acting like he's about to go completely crazy. Edward spends an entire month in which he doesn't smile, he acts like the end of the world is coming, pulling desperate faces, sobbing and lamenting, and (despite they hate each other's guts) guess who is the first person that makes him smile and laugh after all this? Jacob. Awww.
Many fans (or anti-fans) joke about this, saying that Bella wants Edward and Jacob to be friends, because she has hidden fetishes and she actually desires to see them... doing stuff.
The film version's actors don't seem to mind, either. When Pattinson and Stewart were accepting the People's Choice Award for 'Best Kiss', Pattinson went down into the audience and kissed Lautner in celebration, because he didn't really feel like kissing Stewart and giving their rabid shippers ideas.
Horus and Set from Egyptian Mythology, in what might be the oldest known example: it comes from a text of the 20th dynasty in the New Kingdom, c. 1100 BCE. Horus tricked Set into ingesting his semen in order to degrade/humiliate/dominate him. When all the gods got together, the sun god commanded Horus's "essence" to reveal itself, and Set glowed, shaming him in front of everybody... while Set failed an attempt to do the same to Horus. To make it worse, Horus is Set's nephew.
Harry/Marcone. Harry Dresden's a bribe-proof wizard P.I. who's BFFs with a police lieutenant; 'Gentleman' Johnny Marcone is a supernatural-savvy mobster who rules Chicago's crime syndicate. Harry hates Marcone on principal... yet knows his human side better than anyone and swears him to be honourable. Marcone, for his part, can't stop Harry's meddling and snooping, but has also fought by Harry's side against supernatural threats at times, putting his own life at risk. At one point, Harry gets Marcone to stay in a dangerous situation by appealing to his better nature, calling him 'John' and actually begging. Earlier in the same book, Marcone trades his help for hearing Harry say 'Pretty please.' Their dialogue frequently takes the form of almost friendly banter.
In Fool Moon Harry puts the worst possible interpretation on Marcone's order he (Dresden) be taken alive. Readers have their own ideas on the subject.
In a short story set after Changes, Murphy and the werewolf Billy try to get information out of Marcone. At one point, Billy scornfully threatens Marcone, as he knows Harry does frequently- and Marcone calmly orders his bodyguard to shoot Billy's hand. As Billy is writhing in pain from the shot, Marcone tells him disdainfully:
It's worth noting that everyone who has made Harry a tempting offer of power and wealth to work with them, from Marcone to Nicodemus to Queen Mab herself, has been thoroughly and repeatedly rebuffed. With the exception of Lara Raith. In Turn Coat, when she makes an offer of partnership, he doesn't outright refuse.
In that same scene, Lara states that one of her primary goals is for Harry to voluntarily submit himself to her.
Plus the scene in White Night where, as mentioned before, Lara and Harry kiss. Harry expressly describes the kiss with intense detail as to its effects on him.
Harry admits to at least two people, Thomas and Madeline Raith, that he finds Lara to be attractive. In Madeline's case, he told her that Lara sitting down was even sexier than Madeline slinking across a sex club and feeding on someone. He also notes a couple of times that his attraction to her may not be entirely be because of her succubus nature.
Also, see their conversation in Blood Rites, where they have a long, frank discussion about Harry's trauma, heroic motivations and self-esteem issues while teaming up against another villain. Harry, being the distrustful, lonely man he is, has been this open about said issues with...about four other people over the series' course, all of them family or really close friends. And then Lara caps it off by saying that when Harry finally gets too disillusioned to keep heroing, she'd be happy to take him in as a pet/slave. And Harry acknowledges in narration that he might accept her offer someday. Too bad Mab got there first.
Also worth mentioning: Maeve has offered to have Harry's child.
Ma'elKoth and Caine of The Acts of Caine. Technically Ma'elKoth is asexual (or so he says), but his obsession with Caine is definitely at stalker levels. Caine himself lampshades the trope by commenting in 'Blade of Tyshalle' how Ma'elKorh acted like the other woman after his marriage to Pallas Ril, and that Pallas seemed jealous when he and Ma'elKoth spent time together. Ma'elKoth even admits love of Caine (in a 'best enemy' sort of way.
Caesar and Brutus in the last book of the "Emperor" series.
Rare heterosexual example: Luke Skywalker and Mara Jade. The first time they meet, Mara admits she's going to kill him. Ten years later, she ends up marrying him instead.
Love triangle example: The Zekk/Jaina/Jag triangle. Jaina and Zekk are Joiners, corrupted by the Hive Mind insect aliens, and Jag is on the side of the Chiss. Zekk even has a fantasy about the three of them in a threesome.
Fate of the Jedi: Many people had latched onto Ben and Vestara as a couple, before they had even met. Now that they have met, it's even more popular, and they spent much of Allies getting Strangled by the Red String. They're actually a semi-couple now: Vestara wants to turn Ben to the Dark Side, and Ben wants to turn her to the light side. Ben's currently acting cold to her because he found out about the aforementioned Dark Side plan. After the events of Vortex, Vestara can never go back to the Sith, and freely decides to stay and help out Luke and Ben. This, and her saving Luke and Ben's lives three times, makes her seem more like Defecting for Love than this.
Legacy of the Force has plenty of heterosexual Foe Yay. First, there's Luke and Lumiya, which goes back to the Marvels. Secondly, there's Ben and Tahiri. She actually sticks his hand in his shorts. And since Ben's 14 and Tahiri's like, 30, consider the squick.
During the Clone Wars, Obi-Wan Kenobi and Asajj Ventress certainly have a share of this. In the novel The Cestus Deception, Ventress is fixated on him to the point where she doesn't even seem to notice Kit Fisto, the Jedi he's working with. Someone watching her speak of him has this to say in the narration.
There was a flush in her face that Trillot recognized. It was lust. No mere physical passion, although a nameless, fleshly hunger burned within her. It was like lust turned inside out, and it burned inside this strange woman like a fire she could not extinguish.
Warrior Cats has its share of this. Tigerstar's last words to Firestar before he leaves the Clan are, "Keep your eyes open, Fireheart. Keep your ears pricked. Keep looking behind you. Because one day I'll find you, and then you'll be crowfood." Obsessed much? And then, as Tigerstar dies, Firestar realizes he wishes his mortal enemy had lived.
Not to mention Firestar and Scourge, who were actually half-brothers, though they never knew it. Their lives were somehow both parallels and opposites; and what more does one need for a shipping than two characters having something in common or being polar opposites?
And if you consider FirestarxScourge a possibility, TigerstarxScourge has to have crossed your mind. After all, Scourge remembered him, well enough to recognize his face several years later. Tigerstar was one of the main reasons he was driven to such cruelty. And Scourge was completely obsessed with revenge.
Then there's Brambleclaw and Hawkfrost, also half-brothers. Brambleclaw chose loyalty to Hawkfrost over loyalty to the cat he loved. He believed in him up until the moment Hawkfrost tried to make him kill Firestar, and was completely shocked then, despite all the signs being there.
Brambleclaw and Ashfur, rivals for Squirrelflight's love. They've both had periods of absolutely insane hate and jealousy of each other. Perhaps it wasn't Squirrelflight they really wanted, after all...
The line "My quarrel is with you, Squirrelflight"?
Jacky and Clarissa from the Bloody Jack books. This becomes even more obvious when they have a Fake-Out Make-Out to distract some bad guys... and Clarissa seems to like it.
Another rare heterosexual example: Geronimo Stilton and Sally Ratmousen from the Geronimo Stilton series. The best canon example is that even though he describes her as his worst enemy, he still invited her to his Christmas party, and she gave him a gift labeled "To my Friend-Foe." (And the accompanying illustration clearly had her in a Tsundere stance.)
A parody "Motivational Poster" of The Wizard of Oz has the Wicked Witch leering at Dorothy that reads "This probably wasn't what L. Frank Baum meant with 'I'll get you my pretty!,' but it won't stop the slashers." Funnier since Baum threw a surprising amount of Ho Yay and Les Yay into "standard" Oz, and that Gregory Maguire all but grabs it and runs marathons of it. Not to mention that Ozma starts life as a boy.
In the Dragonrealms books by Richard A. Knaak, we get subtext...and some more subtext...and topped off with subtext of Griffon x Shaidarol/D'Shay. Examples: Griffon basically chased D'Shay all over the place, whenever D'Shay is told the Griffon is near, he gets all giddy. Nobody gets THAT excited over a chance to kill someone else.
Explicit (although couched in terms of references to rods) in the chapter of James Branch Cabell's The Silver Stallion where Guivric meets his "appointed enemy".
"Come, come, my enemy!" cried Guivric, "Hatred- since, as you tell me, this is hatred- is throbbing in me now as a drum beats: and I would that we two might encounter!"
Daine and Rikash start their Foe Yay in Wolf-Speaker, and it intensifies in Emperor Mage. (The potential Squick only gets squickier when you remember that Rikash suggests that Daine try shapeshifting into Stormwing form ... a form she'd be trapped in should she do that.)
She [Daine] didn't think he'd get her into trouble, enemy or no. She did have to admit their talks here weren't hostile - more like the exchanges between friends who enjoyed a good argument.
Rikash (to Daine) "I never know what to make of you, [...] I suppose I never will."
"In the doorway, Haley turned. 'Wait for me, Cataffy. You belong to me. And soon, I'll be coming back to collect.' He spoke very softly, but somehow Solid Snake knew that, hidden away somewhere, Col. Cataffy heard his words."
How could you not interpret that as Foe Yay? Especially after watching this dramatic reading and the accompanying illustration.
Explicit, pardon the pun, in the Dragonlance Chronicles between Tanis Half-Elven and Kitiara uth-Matar, to the point where they actually consummated their affair, multiple times, despite being leaders on opposite sides of the war.
Another D&D novel example: Strahd von Zarovich and Jander Sunstar in Vampire of the Mists. Also Ho Yay.
In the Outlander series, there's Captain John Randall towards Jamie. At first, it's more subtle Foe Yay, mostly consisting of Randall having a dreamy look on his face every time Jamie shows defiance and resistance towards him, culminating in Dougal describing Randall's look as a guy who's hot on a girl. And then, Randall shows that these impulses actually extend to being out-and-out sexual, revealing his desire for Jamie to "become his"... which eventually results in poor Jamie getting imprisoned, raped, and beaten (as part of certain scenario that Randall is into) repeatedly. It gets worse when Randall is actually revealed to have probably been genuinely in love with him, in his own messed up way.
In the Batman novel Fear Itself, Scarecrow gets in on the Foe Yay that's usually the Joker's territory in comic-land. He takes a horror writer hostage in his own home, makes him teach him how to write horror, and has some very Stalker with a Crush dialogue with said writer. But then it turns out that he was only doing all this to torment Batman - which he does by attempting to kill Batsy's current love interest. Hmm ...
In the Hork-Bajir Chronicles, Esplin9466 (aka as Visser Three) describes the heroine Aldrea as beautiful and rambles on in the text about wanting to tell her how beautiful and awe-inspiring he found her during battle... after having invaded her brain and 'made her body his own,' of course.
Some of the dialogue between Taylor and Tobias can fall into this territory, although generally she's far too cold and generally unpleasant for it to stick.
Not to mention Edriss/Esplin. They were technically on the same side but hated each other's guts, or claimed to.
Canon example in a sequel to John C. Wright's The Golden Age: Atkins eventually falls in love with a female copy of himself whose mind has been infected by the enemy.
Stel Pavlous' Gene has the two leading characters (North and Gene) destined by fate itself to be reincarnated solely to find the other, and kill them. Having been reincarnated over thousands of years, the sheer obsession to seek and destroy the other has become ingrained into their DNA. Gene even infects him with drugs (when he could have just killed him) that trigger Norths' deepest genetic urges to reawaken his memories of their 'game' so they can begin again.
In The Butterfly Revolution, Frank seems to favor Winnie, such as how he constantly compliments Winnie's intelligence. He's also very obsessed about keeping Winnie a part of the revolution, even though he knows Winnie is counterrevolutionary.
Frank never took counterrevolutionary actions personally but when Winnie resists, he is hurt. Frank almost cries when he publically demotes Winnie. He also becomes "both mad and sad" when Winnie resigns.
It doesn't help that they first met when they were skinny dipping...
The Party invokes this in 1984, with the purpose of the Two Minutes Hate being to channel the citizens' sexual impulses into hatred.
Captain Ahab has at least twice the subtext of most Foe Yay examples. But then again, Moby-Dick is a whale...
Vorkosigan Saga started off as a Fan FicHo Yay / Foe Yay of Star Trek with a federation and klingon commander trapped on a planet and falling in love. Eventually they became Aral and Cordellia, but very much are still defined by the initial foe yay of being opposing battle commanders who fell in love.
The Pendragon Adventure series by D.J. Mchale has a lot of this, both with Saint Dane/Press and Saint Dane/Bobby. It's slightly creepier with the latter, considering Bobby was fourteen in the first book.
They may not actually hate each other but Henry Huggins and Scooter McCarthy, at least from Scooter's side of it. He's always picking on Henry but is always wanting to do things with him and can't seem to stay away. It just seems like he has a crush on him.
The Chronicles of Narnia has Aslan, and the White Witch. Well, Jadis isn't a human (she is a hybrid between an evil spirit called a jinn, and a giant) and Aslan is a talking feline. Heck, even Neil Gaiman ships them!
It and Bill Denbrough from Stephen King's IT. Especially when It pins Bill to the floor twice.
In the Miss Marple book "A Pocketful of Rye", Mary Dove (who's one of the suspects for the murder, and has various guilty secrets of her own) almost seems to be flirting with Inspector Neele.
The second Mistborn book, "The Well of Ascension" has a pretty large amount between Zane and Vin. One of Zane's objectives throughout the book is pretty much to get her to break up with Elend. He also tries to convince her to leave with him, they go and attack a keep together, and then when Vin makes her final decision to stay with Elend (after briefly choosing Zane), he kisses her, and then stabs her. And then she kills him.
Sort of, but not really Katniss and Peeta in the first book of The Hunger Games trilogy. They zigzag from being acquaintances with a deep-rooted past, to Katniss doubting Peeta's kindness, then trying to be amicable with each other, then to Katniss distrusting Peeta again and being upset with his public confession, then briefly making up before the Games, and then to Katniss believing Peeta has betrayed her for the Careers before they trust each other again and eventually fall in love.