Yuma and III Arclight during Episode 46; after breaking into Yuma's house (yes, breaking in) III is invited to stay for lunch. Justified in that the Arclight family aren't the main villains, also that III is the kindest of the family and feels the most guilt about what he and his family have done. Though, it's not only limited to this example/this specific duo, as there are many others from Yuma with other antagonists.
Later, Yuma and Gilag team up for a friendly tournament, although Gilag had no choice and his life was in danger, unbeknownst to Yuma.
Ranma ˝: The title hero has this relationship with all his enemies/rivals. One minute they'll be trying to kill Ranma, the next they'll be eating dinner with him. Mostly this is due to their respect for each other as martial artists, and Ranma's casual nature and confidence. Others are generally either plotting against him during dinner, or else just doing it because it gets them close to Akane.
Happens in episode 19 of the original Mobile Suit Gundam, when Zeon lieutenant Ramba Ral and his subordinates buy Amuro a meal despite apparently knowing that he's a Federation soldier.
Later in the series, Amuro is visiting a neutral colony and his electric car bogs down in some mud. Who should happen to stop and help out? The Rival Char Aznable, of course. In this case, they're both in uniform at the time and of course Amuro recognizes Char (it's kind of hard to miss a man in a custom red uniform and large silver mask), but all Char knows is that Amuro is a young Federation soldier and not the pilot of the "White Devil" that's been a thorn in his side for months (though he does later make the connection).
Again in the original series, mixed with a Worthy Opponent moment: after their plan to blow up the Gundam narrowly fails, a group of Zeon soldiers dresses in civilian clothes and comes to say hi. Bright immediately understand they were the guys who planted bombs on the Gundam, but shuts up and lets them go.
A similar version happens in Mobile Suit Gundam SEED when an incognito Andrew Waltfeld has a friendly debate about kebab sauces with Kira and Cagalli, then invites them back to his place to give Cagalli a dress to replace the one that was messed up in a terrorist attack. Of course, at this point, Andy reveals that he's the Desert Tiger of ZAFT, and has known that the kids are with the Earth Alliance the whole time... Ironically he ends up helping them in the end with little ill will towards Kira for killing his girlfriend.
Happens again in After War Gundam X in episode 20. While on shore leave at an industrialized island, Hard-Drinking Party Girl and Dark-Skinned Blond Toniya ends up becoming friends with only recently recovered ex-Yandere Ennil El, who has spent most of the past three arcs trying to kill Garrod. They have a very good time together, neither one aware of the other's identity... and then Ennil finds out. Even after that point, she and Toniya still view each other as friends and Ennil does eventually undergo a Heel-Face Turn.
In a lesser example, Gundam Wing gives us Zechs. Viewing your rival as a Worthy Opponent is nothing new to Gundam, but Zechs goes beyond that by rebuilding Heero's self-destructed Gundam so they can have a fair fightnote Which includes lying to his superiors about destroying it and giving it back to Heero when all is said and done. When he finally meets Heero face-to-face, Zechs is about as nice to the boy as he gets with anyone while still maintaining his mask.
Tower of God: Ja, Goseng and Miseng are very nervous when they are sitting face to face with the rebellion fighters of FUG, eating fruit together.
Happens, sorta (it smells more like a negotiation and it's actually a trap), when Fate and Negi go to a coffee shop. The two of them then get into a heated arguement, with magic and power flying around, over which is better: coffee or tea.
Earlier in the series, Negi is taking care of Evangeline while she is sick, afterwhich she stops skipping classes. Later, the class is holding a fairwell party for Chao in the middle of her diabolical plan to reveal the existance of mages. The girls who'd just fought her have trouble believing she is the enemy when seeing her be light-hearted and friendly. The series rarely has straightforward villains.
The Team Rocket trio in Pokémon occasionally partake in this, perhaps most blatantly in one episode where everyone enters a orienteering contest. James wins.
Kenichi ends up in this situation when he thinks the very imposing Ethan Stanley is going to challenge him to a fight, and instead they end up discussing non-violent compromises over tea. It ends up he's a combination Anti-Villain / Punch Clock Villain who's only fighting to help his annoying sister. What makes this situation even funnier is the fact when, just as Ethan is about to tell Kenichi his offer, he suddenly gets summonned by cell-phone to go on a burglaring mission and, as Kenichi is unwilling to suddenly part from Ethan, he accompanies Ethan on this mission as a sideline observer! Immediately after the mission is over, the interrupted conversation continues.
While, unfortunately, the non-violent compromises are not used, they still sit down to tea several more times. You gotta give the guy credit for how hard he tries to kill Kenichi even though he's so much nicer to Kenichi than Kenichi's supposed "best friend" Nijima. Kenichi even brings the entire class to the airport to see Ethan off because he thought just disappearing would be too sad for such a nice guy.
This happens quite a lot in Spiral. Although it often does end up ugly, most of the time the opposite factions tend to just discuss their strategies, taunt each other, and/or sympathize with each other. Examples: After Kanone called Eyes to confirm that he's going to try and kill all of the Blade Children, Eyes goes to fetch him at the airport - Kanone isn't surprised. That one ends up very ugly though. They call each other regularly, even in the middle of life-or-death battles, and have tea once it's over. Before the big fight, Kanone also holds non-violent discussions with his 'schoolmates' Kousuke and Ryouko (although his attempts to do the same with Ayumu and Hiyono always end up threatening or more). Hizumi and Ayumu live together and have lots of fun, despite the fact that destiny says the latter must one day kill the former. In Alive, Amanae lives for some time with Imari, then Kousuke and company.
Busou Renkin has Kazuki, Tokiko and Captain Bravo eating at a burger joint with Papillion.
In one episode of 009-1, the title Agent 009-1 Mylene Hoffman was being hunted by a highly skilled hitman who only worked during the day, and refused to fight her at night. So for several days they both tried (and failed) to kill each other during the day, and acted civil towards each other at night, even having drinks and going out on at least one dinner date. On the last night, after another long day of trying to kill each other, Mylene even invites him to her room and has sex with him. She is eventually able to kill him in their next fight.
Death Note: May as well call this trope "Tennis with Kira". (Though L does it to test Light and vice versa; the intensity of the match is nothing compared to the mental tennis required to follow the I Know You Know I Know.)
Inverted in the Yu-Gi-Oh! universe, where the villains usually try to accomplish their goals by competing against the heroes in serious and occasionally deadlyCard Games, and even nonthreatening duels are anything but friendly, even if its between characters that normally;are friends.
Hao/Zeke and Yoh Asakura from the Shaman King manga go to a café and talk over a cup of coffee as to why they're doing what they're doing. The absurdity of this little talk is even lampshaded by Ren and a few others who question Yoh's judgment.
And in Sonic X he actually gives Sonic shelter after finding him knocked out from a recent battle (while he was jogging down the beach no less). The comic adaptation takes these moments Up to Eleven, most notably where he appears at Chris' pool party.
Done with great effect, as the protagonist Lelouch and his eventual rivalSuzaku were close childhood friends. Upon meeting up seven years later, they start going to school together, hanging out with Lelouch's sister...and then fighting each other in giant robots in an attempt to change Japan, for better or for worse.
In addition to that, another one of their classmates is Kallen, Lelouch's ace pilot and in the second season, Brittanian knights Gino and Anya join the school. Gino represents this trope particularly well. The fact Kallen repeatedly tries to cook his Humongous Mecha from the inside out with him still inside is absolutely no reason for him not to try and have a friendly schoolbuddies relationship with her. Though there is hints that Gino would much rather be Dating Catwoman.
Axis Powers Hetalia has some comic strips based on the WWII Christmas Truces, as described in the Real Life section. And depending on the time period the strip is set in, nations that were enemies in other strips will be friends/co-operative/tolerant of the other's presence, as in real life.
Medaka Box: Puppet master Anshin'in is genre-savvy to the point of approaching Medaka when she's alone, outright stating that she's trying to invoke this trope. They spend the rest of the arc playing sports together and going to the hot springs. It turned out to be part of a convoluted master plan to remove Medaka's plot armor by changing the genre of the manga and demoting her main character status. As a result of being essentially omnipotent and winning at everything she does, she's gone kinda crazy and thinks she lives in a comic book.
In Bokurano, Misumi Tanaka, a military officer, says she has met military officers from other countries before, and she is aware of the possibility that her country and theirs might go to war.
In Is This a Zombie?, Naegleria agrees to help the heroes fight Chris. Later, she and Chris have drinks together, noting that they are both "off the clock" but will be enemies tomorrow.
At one point in Fate/Zero, Rider shows up at the Einzbern Castle not to duel with Saber, but to have a few drinks with her. And he brought Archer along for the ride, who provides wine from his private stores. They talk of what it means to be a king (As they are Alexander the Great, King Arthur, and Gilgamesh) before the party is broken up by Assassin.
An Astro City special has the Samaritan (an Expy of Superman) meet with Infidel, a foe he exiled to a pocket dimension to keep him from destroying reality, once a year for dinner. The fact that they meet the occasion with virtually the exact same thoughts and feelings indicates they're really Not So Different. Note also that this was the result of the realization that if they had continued to struggle against one another, neither of them would ever be able to win since they're so evenly matched. Instead, they're fairly content to just use words to try to convince each other to come over to the other side.
In the Black Adam mini-series, he and foe-turned-friend-turned-foe Atom Smasher meet in a restaurant, both in their secret identities. They don't fight, though they almost come to blows. Amazingly, this is actually character development, showing that both (or at least Atom Smasher) have moved past the whole Khandaq affair.
In Teen Titans, Deathstroke and Beast Boy meet in a coffeeshop to discuss the death of Terra. This happens AFTER Beast Boy tried to kill him (and was unable to go through with it).
Marvel Comics' estranged Titan brothers Eros (good) and Thanos (evil) meet on good terms once every year, as a favor to their father Mentor.
The Flash occasionally has such moments with his closest foes, collectively known as "The Rogues Gallery". One afternoon the Trickster and Captain Cold are attempting to freeze the city. Then later, they and Flash go out for drinks.
The Flash, however, does not have this relationship with Gorilla Grodd, Zoom, or Kadabra because It's Personal. Grodd led to the creation of the second Zoom, Zoom caused a Convenient Miscarriage for his wife, although it was Hand Waved later, and Kadabra had already tried to erase his wife from existence. The other villains of the city tend to just be trying to make a (dis)honest living or tried to reform and failed.
The current miniseries Rogue's Revenge has tried to Retcon the death of Bart Allen (who was The Flash at the time) by saying that The Rogues didn't know what they were getting into, and had been tricked into it by Inertia; one of their regular rules is, "Never kill a speedster." And now they're going to even the score... Before that, after Wally West's identity became public, Captain Cold (the "leader" of The Rogues) decreed that no-one was to ever harm a member of his family.
In Justice League Unlimited, this much friendlier relationship is shown when he simply sits down and convinces the Trickster to take his medicine again (after Orion was about ready to administer his form of interrogation).
It also comes up in Batman: The Brave and the Bold, when the Rogues flat-out admit they miss the vanished Barry, compare Bats and the other Flashes unfavourably to him, and come close to tears when he returns.
Professor Xavier, leader of the X-Men, and Magneto, their arch-nemesis, were once best of friends. Occasionally, they still find time for a game of chess or a philosophical discussion in between Magneto trying to kill Xavier's students.
In the Ultimate Universe, Xavier visits museums with Quicksilver and Scarlet Witch when they lead the Brotherhood of Mutants during Magneto's death. Such places are neutral ground. Magneto and Xavier are not as friendly in this universe, unless the former is brainwashed.
At least one story has Bats visiting Arkham Asylum to play chess with Two-Face. This is at least somewhat justified, as canonically Harvey Dent was a friend or at least acquaintance of Bruce before the accident that turned him into Two-Face.
Oddly enough, in a lot of continuities, wanting this sort of relationship with Batman is the Riddler's character motivation. He even once gave an interview with reporters where he said he doesn't want to hurt anyone, he just wants to play puzzles with Batman. Batman is always reluctant to give him any attention, though.
In a Fantastic Four one-shot, Reed Richards and Dr. Doom resumed an unfinished chess game from their college days from memory, even as they were fighting each other. And earlier in that one-shot, before they began fighting again, they were quite civil with each other.
In the Flashback Universe, Saturn Knight and Lady Nemo are arch-enemies and ex-lovers still secretly pining for one another; They meet peacefully once every year for reasons unclear even to themselves.
While her rogues are inconsistent at best, she and longtime foe Circe occasionally engage in this, likely a result of that time that Circe brainwashed herself into becoming Diana's best friend. In the only part of the v3 reboot that made any sense at all, she seems to consider her stealing of Diana's powers and job to be doing her a favor, and they confide their respective emo to each other before Circe disappears after the fight.
Another issue has her talking about men with Giganta.
The supervillain Angle Man attended Donna Troy's funeral, though at this point he was effectively retired.
In an early issue of Sonic the Hedgehog, Snivley and some Swatbots interrupt a hockey game the Mobians are playing simply because they wanted to play themselves. Robotnik finds out and ups the stakes on the game, but Snively really wanted to play for fun.
Zot! has a rather extreme example. 9-Jack-9 is Zot's archnemisis responsible for the death of Zot's parents. He also visits on Zot's birthday on friendly terms and plays in his Uncle Max's band. Even though he killed Zot's parents. It should be noted that neither Zot or Uncle Max were aware of his identiy as a bandmate, and Zot quite openly hates him and is fuming when he shows up at his party. The canoncial explanation for why Zot or Uncle Max never do anything is because they're just that nice.
As shown in the trope image, the superheroes of The DC Universe once faced off against the villains in a "friendly" baseball game. All to settle a bet between the villainous married couple, Sportsmaster and Huntress, over "whether villains can win." Uncle Sam and Amazo handle umpiring duties. It Makes Sense in Context... barely.note DC Super Stars #10 ("Strange Sports Stories")(1976)
An Elliot S! MagginSuperman story has Lex Luthor always escaping on a certain date each year, eventually Superman figures out he's trying to celebrate the birthday of Albert Einstein, one of his heroes. Superman arranges for himself and Luthor to have a private tour of the Einstein section of the Smithsonian. Luthor actually tears up as he sees the statue. As Luthor is taken back to jail he tells Superman, "Thanks for everything!" Definitely a Crowning Moment of Heartwarming.
Mickey Mouse and Pete seem to have this relationship, especially in the Disney Italia comics. In one issue, Pete will have tried (and failed) to kill Mickey. The next, he'll be at Mickey's, asking if he could come in to watch TV. And Mickey will invite him in, because, well... it'sPete.
The lions in Pearls Before Swine try to be friends with Zebra, even though they admittedly would eat him should their wives catch and kill him (female lions are the real hunters). To their credit, they warn him about his personality traits that make him look like easy prey — like driving a Prius and subscribing to Oprah's Book Club.note There is a National Geographic story showing night-vision shots of male lions killing zebras. Lions are ambush predators and their manes make it hard to surprise their prey in full light.
In Toy Story 2, Utility Belt Buzz is actually last seen playing catch with Emperor Zurg after the latter is revealed to have survived a fall into an elevator shaft. Well, apparently, Zurg is Buzz's father.
To a lesser extent, there is Woody and Buzz who often fight against Hamm and Mr. Potato Head in Andy's playtimes, but (usually) get along with each other outside of playtime.
In Wreck-It Ralph, Ralph and Felix are reasonably polite with each other when they aren't playing their game, though averted in the case of the Nicelanders who are rude, wary or insensitive towards Ralph.
And by the end of the film, they're legitimately friends, with Felix even referring to Ralph as "brother" a few times.
Films — Live-Action
It's certainly a James Bond trope. Bond has played cards with villains in the past, but the main difference is that this is usually before they start trying to kill each other. Special mention goes to:
Superthief (DeNiro) and supercop (Pacino) sit down for coffee in Heat in one of the most iconic examples ever.
In the classic film Pepe Le Moko and its American remake Algiers, Inspector Slimane makes a friendly visit to the title jewel thief daily, all the while developing a Batman Gambit to put him in jail.
God and Satan (both played by George Burns) play Poker in Oh, God!, You Devil. Of course, it's not exactly a friendly game, given that the stakes are a person's soul. God wins by bluffing.
In What Did You Do in the War, Daddy?, an Italian village is having a festival. Rather than fight them (it was set in World War II after all), the Allied forces party with them.
In Renoir's World War One POW film La Grande Illusion, the French and German officers are friendly, with mutual acquaintances. This is quite a common trope in prisoner-of-war movies, but it also has a political subtext.
At some point in classic French gangster comedy Les Tontons Flingueurs, a couple of gangsters show up at a rival's house, intending to fight. Since the rival's niece is having a party, the middle-aged gangsters all end up in the kitchen, buttering toasts and getting drunk on "the weird stuff".
Being Victorian Gentlemen, Sherlock Holmes and James Moriarty share a friendly game of blitz chess and trade snark while discussing their plans to thwart the other.
In The President's Analyst, American agent Masters and Soviet agent Kropotkin are old buddies. They even place a wager on who will catch the fugitive analyst first, the loser having to buy dinner at a restaurant in Albania - the Russian promises to leak information so the American will be sent there.
In the Renaissance epics of Charlemagne and his Paladins, Orlando Innamorato and Orlando Furioso, the Christians and Saracens are engaged in a long world war that can only end with the extinction of either Islam or Christianity. Rulers on both sides invite enemies into their homes, during which everyone is quite civil.
Older Than Print: In a 12th-century Arthurian romance by Chrétien de Troyes, Lancelot is in an epic contest of arms with another knight (possibly in Black). After swinging at one another for quite some time, they take a break, have a chat, get their breath back, and start back up again. They're quite civil. Quite like a certain film.
Aziraphale and Crowley's relationship in Good Omens started out like this and only got closer. By the time the story gets underway they've been actively defying both Heaven and Hell for years, and only participating in the angel/demon feud to keep up appearances.
The reason given for their "Arrangement" is that they realised "they have more in common with their immediate opponents than their remote allies" and a certain acceptance of the inevitable, rather than ideological slippage. Aziraphale honestly believes in his cause and Crowley enjoys his work, but neither sees what they do as particularly important in determining the contest between Good and Evil. Both are also scared of the punishment leveled at dissenters by Heaven and Hell.
In The Dresden Files Mother Summer and Mother Winter, the two most powerful queens of their respective fairy court live in the same cabin and get along fine, despite their respective courts being at war.
In Roger Zelazny's The Chronicles of Amber the bitter antagonists like nothing better than a good old natter. In effect the opposing, godlike immortal they are facing at swords length is still family, and killing them immediately would foreclose the news on plots, treachery, births, deaths and marriages. More generally the series features an unusual amount of civil interaction between characters in such deadly opposition that normally you would expect just threats and violence.
This is mostly explained by the curse power that all Amberites have enabling them to karmically nuke their adversary if they get pissed enough. Therefore, they need to play everything as "strictly business" to avoid karmic nuclear war that would destroy Amber. Plus, they are all family.
In Going Postal, Reacher Gilt is more than willing to have a little chat and pay the bill for Moist von Lipwig's dinner in Ankh-Morpork's most expensive restaurant, despite being the main villain for the book. Even though he is a tad surprised to see him there because he's just sent a hired killer to maul Moist and torch the Post Office. Oh dear.
The Harry Potter parody series Barry Trotter did this once in Barry Trotter and the Unnecessary Sequel, when Lord Valumart showed up for Barry's thirty-eighth birthday party as an invited guest.
In Anne Rice's Memnoch the Devil, Lestat overhears God and the Devil chatting in a coffee house.
Magician Roogna and Magician Murphy in Castle Roogna — part of Piers Anthony's Xanth series — are quite civil to each other, and consider their battle for rulership of the humans in Xanth akin to a strategy game or contest. Others might see it differently, especially when Murphy's magic talent lures two opposing forces into having the final apocalyptic battle of their war at Castle Roogna.
In The Hobbit, Bilbo and Gollum tell each other riddles. (Though it's clear there, and made even moreso in The Lord of the Rings, that Gollum would've happily killed Bilbo, and the latter was just trying to buy time so he could get out of there.) Riddles are also Serious Business in Middle Earth.
One of the best moments in J. P. Martin's Uncle series is when Uncle's sworn enemies show up and they all celebrate Christmas together. It's casually mentioned that this is an annual tradition. Of course, the enemies get food, presents, and a chance to observe the house / castle / kingdom that they want to take over. But considering how they usually upset Uncle's refined sensibilities, have attempted many times to rob him, have stabbed him with skewers, and enjoy spreading inaccurate malevolent propaganda about him, you do have to wonder what's in it for him. Perhaps just Rule of Funny?
In Warrior Cats, there are gatherings that are a temporary truce between the four clans that happens once a month. However, there are cases where these gatherings can get broken. Also, clans can refuse to join a gathering in several cases.
Mentioned in Letters to His Son by British statesman Lord Chesterfield: "When I was last at The Hague, we were at war with both France and Spain; so that I could neither visit, nor be visited by, the Ministers of those two Crowns; but we met every day, or dined at third places, where we embraced as personal friends, and trifled, at the same time, upon our being political enemies; and by this sort of badinage I discovered some things which I wanted to know." (letter 215)
In The Pushcart War, Maxie Hammerman brings the Police Commissioner to crash a secret poker meeting by the Big Three where they're plotting Maxie's assassination, telling the commissioner that despite their differences, they often sit down for a friendly game of poker. The bad guys quickly figure out what's up, but they can't do anything with the commissioner right there. Maxie ends up winning a great deal of money, as well as the bulletproof Italian car that would have been used in the assassination.
In the James Bond novel Devil May Care, James plays a game of tennis with the villain, though notable for the fact he cheats.
In Being Human, Mitchell and Herrick have a relatively friendly and jovial relationship when they're not arguing dramatically or fighting. After Mitchell and Herrick both are dead, we get Tom and Hal. Tom is a werewolf raised by his werewolf daddy to stake all vampires on sight and treat them as threats. Hal struggles to keep from killing people, but has a very bloody past and is one of the Old Ones, essentially vampire royalty. They eventually get to be pretty good friends.
Star Trek: The Next Generation shows that rival houses of Klingons and their allies have a standing truce while they're in the capital city, and will often get together at the local tavern and drink a few brewskies with each other, all the while jovially teasing each other about how they'll kill each other next time they're on the battlefield. Klingon warriors want to die in honourable battle; it's the most honourable way to die. If you kill a Klingon warrior in honourable combat you are doing him a favour — no wonder they are on friendly terms when they are not actually fighting. They also point out that, in the crowded bar, no-one can really tell who is on which side. They're all just warriors out for a drink.
Colonel Klink and the prisoners often engage in (seemingly) friendly camaraderie in Hogan's Heroes. As senior POW officer Hogan sometimes gets invited to dinner or parties with visiting guests, and occasionally Klink agrees to participate in prisoner recreational activities. One scene has Hogan peacefully playing chess with Klink — he throws the game, but takes advantage of the kommandant's distraction to steal his dinner and later convinces him that he was so focused on the game that he forgot he was eating.
Ethan Rayne taking Giles out for a pint when he finds out Giles was fired from the Watchers Council. And spikes his drink with a potion that turns him into a demon, leading everyone to think that the "demon" killed Giles.
Spike is practically a Go Karting magnet. Nearly every main character, up to and including Buffy's mom, gets a scene where they're chatting amiably with him like he's not evil. And that's before Buffy starts shagging him....
In the 1960s Batman TV series, one of the episodes involves Batman and The Joker facing off in a surfing contest. The Joker doesn't even cheat, sorta. He used some kind of device early in the episode to take all the surfing knowledge from a champion surfer and upload it into his own brain. It didn't help him, though.
In an episode of The Practice, Bobby Donnell is defending an alleged murderer and consults another lawyer who is suing him in relation to another murder trial, asking him if he thinks the prosecution has made its case. He replies that he doesn't think so, and it's presumably his honest opinion; he's watching the trial in order to study Donnell's tactics, but the outcome of the trial doesn't matter to him.
Avon Barksdale coaches an annual charity basketball game against a team lead by his bitter rival in the Baltimore drug trade, Proposition Joe. Even though they are willing to play together, Avon makes clear what their relationship is truly about: "You come back to the West side without a ball, I'm'a light yo' ass up."
When Preston "Bodie" Broadus gets caught by Herc and Carver and they have to kill a few hours, so Bodie the drug dealer plays pool with the police.
By the time the characters in American Horror Story: Coven compete in the Seven Wonders, they've all grown to hate Madison. One of the Wonders is teleportation, which the girls all master. They then decide to take a break from the competition and play a happy game of teleportation tag.
In the Justified episode "Over the Mountain", Boyd Crowder and Tim Gutterson play Scrabble in Boyd's bar while waiting for Raylan to come back.
In an Ultraman Taro focused tourism campaign for Hawaii, Alien Baltan seems to have called off his grudge to enjoy his Hawaiian vacation with the Ultraman family and Pigmon.
Subverted in an anecdote Zoe tells in Firefly: During a battle, the regiment to which Zoe and Mal belonged reached to a stalemate with the Alliance forces. The Alliance forces were besieging the Rebels' entrenched position, and the two forces were so close to each other they were able to call over to each other. The two sides began to develop a rapport of friendly insults and jokes. At once point the rebel soldiers mentioned they had no food. A little while later the Alliance soldiers threw over a load of fresh apples. Each piece of fruit had a tiny detonation charge in it triggered when a person bit in. Half the rebel regiment had their heads blown off.
Skyhooks' "Jukebox in Siberia" describes Marx, Lenin and Trotsky hanging out with Rasputin and the Tsar in a Siberian nightclub. Later, they are joined by the crew of an American submarine. The song also mentions that "if you're CIA or KGB, they might let you in for free", although such actions do seem more reasonable for those involved in espionage work.
Occasionally used as a tactic by athletes as a way to psychologically manipulate opponents via The Power of Friendship. One possible example is Michael Jordan, when he invited Charles Barkley out for golf during the NBA Finals and "befriended" him, giving him an expensive $20,000 earring. Jordan and the Chicago Bulls would eventually defeat Barkley's Suns team to win their third championship.
The World Cup has had some calmative effects at times — see the Côte d'Ivoire truce in 2006.
Former cricketers Ian Botham and Vivian Richards (of England and West Indies respectively) have been best friends since the 1980s, when they were professional rivals.
In some depictions, a few of the Archangels and Demon Princes in In Nomine will get together and talk about the old days while at the same time their servants are elsewhere fighting to the death.
In the D&DPlanescape setting, you might find a celestial deva and a pit fiend calmly discussing philosophy in a tavern in Sigil, and not think much of it. However, Sigil is under the protection of the Lady of Pain, who can keep out gods and flay virtually anyone (including said gods) with a glance. Making trouble there is not a good idea.
Apparently the denizens of the Warhammer world occasionally put down the swords and crossbows to duke it out in a friendly (okay, not that friendly) game of Blood Bowl. It's a very violent sport, sure, but it's still a sport, as opposed to a battle. It has been stated by Games Workshop that the two settings are not the same and the Blood Bowl-verse is actually a alternate universe of the Warhammer world where certain events didn't take place.
One of the many supplements released for Champions, "Neutral Ground", details a private "gentleman's club" called "The Sanctuary" that allows both heroes and villains to join, as long as they agree to not try and pound the snot out of each other while the heroes and villains are both there. One of the most frequent occurrences encountered by players is Doctor Destroyer (The Champions Universe expy of both Doctor Doom and Darkseid) playing chess with an old nemesis.
At curtain calls, villains will hang out with heroes with no problem, even if they're dead.
In Pokémon Live!, in the finale, Giovanni dances with the rest of the cast.
Repeated home invasions and sexual assaults normally lead to restraining orders, not golf invitations.
In Super Mario Galaxy, Bowser even flat-out states that he likes having Mario as an arch-enemy.
He previously stated this in Super Mario 64 DS. Mario is the only character who is allowed to access the final area because "Mario is the only one I [Bowser] can call my rival."
The ending of Super Mario Sunshine implies that Bowser (and now also Bowser Jr.) aren't kidnapping Peach for the novelty anymore — they're doing it specifically because it will give them the chance to fight Mario, who will inevitably attempt to rescue her.
In Mario Party 5, after Bowser is defeated in Story Mode, he reveals his dream: having a strong opponent. He then bids the player a friendly farewell, his dream having just come true.
When you think about it Bowser's been trying to kidnap Peach and beat Mario since they were babies. It's like a routine, if he stopped doing it they'd probably worry that something was wrong. This is implied to be the case in Super Mario RPG, in which the constant kidnappings are mentioned several times and at one point, Bowser even laments being broken out of his routine and reminisces on how the kidnapping attempts usually go.
Mario: Well, you know what dey say, keep you friends-a close, and you enemies-a closer. But dey also say, if you enemy is a gigantic spiky creature, who breathes-a da fire, keep him-a super-duper close!
Best examplified in the intro to Mario Tennis 64, Bowser and Boo barge into the tournament via their sinister battleship and confront Mario and Luigi, before cheerfully requesting a match.
Mario: Hey, let's-a ALL play!
In the Super Smash Bros. Brawl story mode The Subspace Emissary, Peach stops a fight between her partner Sheik and Fox to have tea. Fox instantly becomes their friend. Though since Fox and Sheik are both heroes, it was more of a Let's You and Him Fight situation that Peach defused.
Kirby and King Dedede should count as well.
Really, the game as a whole is a very "fighting" version of Mario Kart anyway. Even after losing a match to long-time nemesis Link, Ganondorf will still politely (if begrudgingly) stand in the background and applaud.
Shigeru Miyamoto: If you're familiar with things like Popeye and some of the old comic characters, you would oftentimes see this cast of characters that takes on different roles depending on the comic or cartoon. They might be businessman in one [cartoon] or a pirate in another. Depending on the story that was being told, they would change roles. So, to a certain degree, I look at our characters in a similar way and feel that they can take on different roles in different games. It's more like they're one big family, or maybe a troupe of actors.
Jade Empire has two representatives of the Way of the Open Palm and the Way of the Closed Fist (the game's rough way of saying "Good" and "Evil") meet once a year to play a game vaguely reminiscent of go. Without any pieces. Or a BOARD. Once you've chosen one philosophy for your own and learn the corresponding martial art, the two conclude their game and vow to meet up next year... if something bad doesn't happen in the time in-between.
Harman and Kun Lan in Killer7. Necessary because they're both immortal; since neither can have ultimate victory, they have to settle for getting best two out of three at chess. Or global thermonuclear war. Whichever strikes their fancy.
In The Sims 2, anyone whom you're furious with or enemies with can be invited to a wedding. And they'll come. And share cake, toast to you and even clap for you when it's over. But next time you see them, they're back to fighting you.
In Final Fantasy VI, after having spent half the game chasing Terra, having sentenced Celes (a former General in their army) to death, occupied Edgar and Sabin's kingdom, destroyed Doma, killed countless Espers, and basically waging war against the entire world (a war which he was close to winning), Emperor Gestahl invites the heroes to a nice and civilized diplomatic dinner, just to show he's not a bad guy anymore. (He still is. The whole thing was a ruse.)
It's worth noting he blamed Kefka for almost everything, even going as far as asking the party what should they do with said Ax-Crazy/Caligula/Nietzsche Wannabe/Omnicidal Maniac, trope overdose etc. One of the options is to execute him, though the correct choice is to leave him in jail. It's also worth mentioning that the cast didn't fall for the ruse and tried to plan for an eventual betrayal. They just didn't realize the actual evil plan in time for it to be prevented.
King Dedede and Kirby have this kind of relationship normally — their adversarial bouts are the exception.
Kirby games do this a lot. For example, Kirby can choose to use his Copy Ability to make a "helper" (for example, Fighter Kirby summons Knuckle Joe), who are friendly versions of the enemies swallowed. Chef Kawasaki is a mini-boss in Kirby Super Star, but in the anime, he gives Kirby a (short-lived) job at his restaurant. In fact, the only characters who are consistently evil seem to be the final bosses.
Not even the final bosses now, Magolor is back in Kirby Dream Collection and seems to have reformed. You could even do some friendly races with him.
Judging by the way the original developers handled the franchise, Crash Bandicoot seems to have a bit of this going on with Dr. Neo Cortex, specifically in Crash Team Racing where the good guys and bad guys are all just go-karting along before the plot happens... and then they all go-kart around some more.
Practically every ending of every installment of Touhou have the main characters sit down and drink tea with the last boss after they save the world from the said last boss. Most of the villains are just Youkai who get it into their head to do something destructive. In fact, Go Karting With Bowser is the entire idea behind Mountain of Faith's Extra stage.
The NES game Eight Eyes shows your character having tea with a boss after defeating him/her.
Dead or Alive Xtreme Beach Volleyball. Characters that would otherwise be at each other's throats just want to relax at the beach. Even characters like Ayane/Kasumi, Helena/Ayane, and Christie/Helena, who all pretty much have a kill on sight method of greeting each other in canon have only a small grudge. Justified though, as it's All Just a Dream by Zack.
There's an old Namco platforming game for the Sega Genesis called Talmit's Adventure, where the leading character, Talmit, had to beat 3 of the Mole King's underlings to save three fairies and their princess trapped in magical orbs, complete with Smooch of Victory. Nothing wrong with that, until you realize that every single boss battle is a Mini-game with lots of The Computer Is a Cheating Bastard. The minigames, themselves prove to be quite entertaining though, even, surprisingly, the Rock Paper Scissors battle with a twist. After beating the last world, you are pitted against the Mole King who plays a variation of Whack-a-Mole against you. The ridiculousness of this is even taken in account by the Big Bad himself, who after losing attacks you and becomes the first and last real boss of the game.
Done quite literally in Grand Theft Auto: San Andreas. The 'hero', C.J. literally kills his way through Mad Dogg's orginization so a friend, OG Loc, can jumpstart a music career. Then, in order to restart Mad Dogg's career (a movie which greatly benefits C.J.) he and Mad Dogg chase OG Loc through the streets of Los Santos...on go karts. In order to get a valued rhyme book back. Apparently Madd Dog cannot make up new rhymes on his own. M.D. has 'so far' not discovered that C.J. was the one to kill his co-workers and leave his mansion filled with bodies.
In City of Heroes, the heroes and villains can fight over an island in Bloody Bay or Warburg, protect/invade Paragon City in Siren's Call, or fight over the future in Recluse's Victory. Alternatively, they can have a drink and go on a few missions together in the Pocket D dance club, work to protect the past in Cimerora and the Midnighter's Club, and fight aliens in the Rikti War Zone.
In one of the endings of The Bard's Tale, The Bard, rather than side with either the demonic princess or the Druids trying to seal her away, tells them both to "sod off" and heads to the nearest tavern. The ending shows him hanging out in the tavern with the undead mooks he's been fighting throughout the game, who actually aren't that bad once you get to know them.
The Hoyle's Book of Games series, by Sierra Entertainment, is a video game collection of card and later board games. In the first game, you could choose opponents from the heroes of various Sierra games. The Third game (the second was a collection of solitaire games so...) also allowed you to sit down and board games with various Sierra villains, such as Sludge Vohaul and Mordack. They generally made villainous comments, though.
In Donkey Kong 64, the 100% completion bonus scene shows the characters as actors. Donkey Kong and K. Rool are seen playing patty-cake.
Rayman M (known as Rayman Arena in the US) has Rayman and his friends and enemies engage in a racing competition, although the canonicity thereof is uncertain. (They can still beat each other up in the battle segments, though.)
Heavy Rain has this with a golf match between Scott Shelby and Charles Kramer.
Played straight in Kingdom Hearts: Birth by Sleep, with the Rumble Racing minigame, as well as some of the Command Boards. You play against Gantu, Captain Hook, Maleficent...
Pokémon Black 2 and White 2 has Giovanni, the Big Bad of the first two games and the main villain of the anime, in the Pokémon World Tournament, due to his old position as Viridian City Gym Leader.
During a Space Route scenario in Shin Super Robot Wars, Hathaway Noa is chatting with Quess Pariya, who wants to know what Amuro is like. Hathaway, confused, says that Amuro is totally normal. Quess says that she's studying yoga, hoping to gain the ability to know what people are like even without talking to them - much like the fabled Newtypes can.
Angry Birds Go: Pretty much the only time the birds and pigs aren't feuding with each other. Case in point, they're racing for a cake.
Phoenix has a Spot of t... coffee with Godot, right after the end of their last trial together in Phoenix Wright: Ace Attorney: Trials and Tribulations. Also, Apollo and Trucy went together to Klavier Gavin's concert in Apollo Justice: Ace Attorney. That said, Trucy is (or had rather become) a huge fan of Gavin's band, and Apollo was never really that hostile towards Klavier anyway — he just doesn't like the loud music. On the other hand, Ema Skye would rather have coated her left arm in Snackoos and eaten it than wind up running security for the gig out of her personal loathing for Gavin, and makes this sentiment loud and clear when she meets up with Apollo backstage.
Oh boy, Phoenix and Edgeworth. They were childhood friends, and Phoenix had sort of centered his law career around an idolized image of Edgeworth as a Protector of the Innocent. They snark at each other a lot, but it's quite clear that they mean a lot to each other, platonically or not, and that they're there for each other when it counts - just look at how Edgeworth charters a private jet to see Phoenix when he hears that Phoenix is in hospital. They count as fairly close friends at the very least, and even though they don't exactly seem to hang out much, this can probably be attributed more to the rather standoffish type of person Edgeworth is than to them not getting along.
Truth in Television: Attorneys are often chummy with each other outside of court, even if they represent opposing sides of a case. It's part professional courtesy and part realism: just because your lawyer fights tooth and nail for your case doesn't actually mean he believes in you. It's what they get paid to do.
One of the side stories, "The Tohno Family Con Game", is about most of the cast playing a game of tag, villains included. Amusingly, the villains are generally more affable toward everybody than much of Shiki's Unwanted Harem. Technically fanfiction, but it was included by Type-Moon on the fandisc.
In a more canonical example, in the very first scene after branching onto Kohaku's route in the original visual novel, Shiki, the main hero, meets the main antagonist who's been trying to kill him since he was a kid, and is a serial killer/vampire/cannibal, and has coffee with him on a park bench while discussing life and how they both fit into the world, and joking with each other like friends. Granted, the villain had just caught Shiki going berserk and killing some people in a back alley. In the end, the villain does try to start a fight, but Shiki tells him that he's superior in a fight to the death, and the villain puts his weapon away and agrees with him, and decides to give up and leave town for good.
This theme is somewhat continued in another side story, "Drinking, Dreaming Moon", where they drink alcohol together and talk about how nice it might have been had the villain never turned evil to begin with, and reminiscing on how great of friends they could have been. But then Shiki wakes up and finds that it was All Just a Dream}... Or Was It a Dream?
In Heaven's Feel, Shirou shares a table at a Chinese restaurant with Kirei Kotomine, by all rights his arch-nemesis, who killed his parents and all of his friends and neighbors and then his foster parent, in basically every scenario, who calmly reveals that he was a villain for the first time in this particular scenario (after Shirou already guessed it). And he offers Shirou some of his Mapo Tofu. Twice.
Lancer loves this trope. In Unlimited Blade Works, he is trying to have a friendly chat with the heroes, and Rin complains that they're supposed to be enemies. He remarks how back in his day it was normal for enemies to dine and party together when they weren't in battle. Rin claims that those days have long went out of style. To which Lancer replies, "Really? This age sure is boring."
In the Fate/Zero prequel, Saber, Gilgamesh, and Rider all have a drinking contest against each other, to "prove who's the greatest king." Meanwhile, Saber and Rider's mortal partners are hiding off to the side and amazed at the proceedings. When the Assassins show up to fight, Rider offers them something to drink, too.
In Heaven's Feel again, Rider has tried to kill Shirou several times already, and saved him once, and just nearly turned all the heroes to stone the previous afternoon, but then she's suddenly eating breakfast with Shirou in his house. He is understandably uncomfortable. Except it's actually because she has no food in front of her at first.
In all three scenarios, Shirou and Rin spend most of the story living together and competing in meal preparation, all the while Rin is constantly reminding Shirou (and you) that they are enemies who will have to kill each other before it's all over. By the way, it never actually happens.
In both Fate and Heavens Feel, after Berserker is defeated, Illyasviel starts living with Shirou for the rest of the story. And even before that, in both cases, she is unusually clingy and likes to play with him in the park. Nevermind that she's been his greatest threat and tried to kill him countless times (and possibly succeeded) up until this point. The True End of Heaven's Feel even has her perform a Heroic Sacrifice to save his life.
Despite the fact that Lambdadelta is working specifically to trap her for all eternity and torture her slowly, that doesn't stop Bernkastel from having sleepovers with her. Subverted. They were actually allies all along, and even implied to be lovers.
Also, Battler and Beatrice have a really playful relationship from the start, which is a little weird. Also subverted, since Beatrice was only pretending to be Battler's enemy as a way of guiding him towards the truth.
In one cartoon, Strong Sad mentions that he and The Cheat play Jenga on Tuesdays. Despite claiming to hate Homestar, it seems that Strong Bad tends to tolerate him more and more as time passes. They even starred in Dangeresque 1: Dangeresque, Too? together. Then again, Strong Bad seems to drag everybody into his Dangeresque movies, whether they want to or not.
On the "Cheat Commandos", Blue Laser invites the Commandos for a Thanksgiving Dinner. The invitation was for everyone, but the team decided not to tell their leader Gunhaver, since he has a hard time relaxing.
In Red vs. Blue, many of the non-story-related comedy shorts feature the Red and Blue teams hanging out together and discussing various subjects from E3 to zombie apocalypses. They're still somewhat antagonistic towards each other, though.
The Autobots vs Decepticons conflict is a lot more light-hearted in Transformers Kre O than the war seen in other iterations of the franchise. Here, they engage in dance competitions and car races.
Happened in Antihero For Hire, though it was a game of chess between two antagonists, rather than between a hero and a villain. However, considering that they're very much antagonistic towards each other as well, it still seems to count. One basically goes "I'll kill you last", while the other responds with "Not if I find a way to mind-control you first, you won't."
There's a related melee scene in El Goonish Shive. The three members of a Quirky Miniboss Squad confront three main characters. The noble one attacks in order to subdue the protagonists before the Big Bad can arrive to kill them instead. The twisted one attacks in bloodlust. The slow one has no incentive to do either, and is left standing awkwardly with the third main character. After a moment they have a thumb war.
Elan: I know that sometimes, the hero has to play baccarat with the enemy, even though logically it would make more sense for them to just be trying to kill each other. What I don't know is how to play baccarat.
Evil Inc. has the two main characters, Captain Heroic and Miss Match, being husband and wife in their off hours, but battling each other while "on the job". This is a case of Slap-Slap-Kiss developing to its logical conclusion, and both of them have to hide their relationship from their associates. They're depicted as actually devoted to their respective ideologies (i.e. while Miss Match as an employee of Evil Inc. is literally a Punchclock Villain, she doesn't fit the usual "Evening Sam/Evening Ralph" characteristics of the trope), but they love each other enough to do what it takes to make it work anyhow (and they do occasionally have arguments about it).
The Spoony Experiment: Dr. Insano and Spoony still apparently live together despite the former having killed the latter (he got better). Insano even fixed Spoony's Atari Jaguar so he could play the Highlander game, although that might not have been a completely kind act.
In Noob Tenshirock is a hacker who wants to get people to stop playing MMORPG by making their gaming lives hell. While he's seen using members of the Noob guild as lab rats from time to time, these events have a 1:1 ratio with him casually sharing tavern tables with them, playing rock-paper-scissors with Gaea and sometimes being quite helpful.
Batmanthe Animated Series: Batman plays poker with Poison Ivy, Two-Face, Penguin, and the Joker. Subverted in that he's disguised as Killer Croc and is trying to find out where the Joker has Catwoman held captive.
A good example is "The Truce Hurts", even though it is short-lived, in which Tom and Jerry, as well as Spike, put their differences aside and get along with each, only to once again be mortal enemies by the end of the cartoon.
There was another episode spanning as a Clip Show, where just Tom and Jerry make a truce. They watch a picture show together, starring themselves, and are then reminded why they're enemies when watching their movie selves humiliate each other. At the end of the episode, the film is planning a scene of "The Truce Hurts" where Tom, Jerry, and Spike are hitting each other, only to stop and watch the real Tom and Jerry fighting in the theater, clearly amused.
Especially exemplary of this trope is the relationship between Ralph Wolf and Sam Sheepdog. On the job, they take every opportunity to try to beat the other to a pulp, but when the day is done, they talk to each other like old chums.
Pegleg Pete (a.k.a. Black Pete, Big Bad Pete, Perilous Pete, Putrid Pete) has this relationship with the rest of the core Mickey Mouse Funny Animal crew. At times he's a genial but gruff neighbor, at other times he's a gigantic hulking gangster. The villain version came first. The neighbor role (e.g. the one you see in Goof Troop) seems to have started as an attempt to soften him up, though it ended up simply coexisting with more ruthless roles.
In a Christmas episode of House of Mouse, Minnie is threatened with mistletoe by Mortimer Mouse. Pete shows up, seemingly about to make the situation worse (in the old days his motives mainly revolved around kidnapping her for himself), when suddenly he swoops in and gives Mortimer a big smooch to scare him off. In what is both an entirely bizarre or an entirely awesome moment, Minnie and Pete high-five each other.
Bluto and Popeye get along great — when Olive Oyl isn't around. But when she gets involved... Unless they get their orange juice. No, really.
The crimefighting platypus Agent P and his archnemesis Dr. Heinz Doofenshmirtz are often seen as very amiable foes, with their roles as good guy and bad guy often being alluded to as mere jobs they have to do. Dr. Doofenshmirtz even goes so far in certain episodes to have Perry sit in a waiting room so the German doctor can finish a plot, or to exclaim to Perry that he doesn't want to fight, it's his weekend off. In an episode, he even says that he considers Perry his best friend... right before Perry uppercuts him out of the spaceship they were on.
The two get even more buddy-buddy as the series marches on. Should Perry happen to show up on a day when Dr. D doesn't have an evil scheme planned, Perry winds up helping him in tasks such as decorating for his daughter's birthday party or renewing his driver's license. Perry once even used the failed -inator of the day to turn Doof into an anti-establishment rapping DJ, helping him look cool in the eyes of Vanessa and her goth friends.
The same can be said for episodes where Candace willingly participates in Phineas and Ferb's activities without trying to bust them for it.
Mr. Krabs and Plankton in SpongeBob SquarePants play cards together. Which, of course, is part of Plankton's scheme to throw the card games to fool Krabs into putting something valuable, like SpongeBob's contract, on the line. In the episode "Band Geeks", Krabs and Plankton both perform in Squidward's band. SpongeBob frequently partakes in this. Don't be surprised if Plankton is among his guests at one of his parties.
On The Fairly OddParents, an entire episode is based around the fairies, the anti-fairies, and the pixies competing in the Fairy World Games. Also, Juandissimo gets along great with Timmy when Remy's not around.
Kim Possible and Shego seem to mutually respect each other, despite their normal levels of animosity. They've been known to chat in the middle of fights. In the episode "Sick Day" Kim and Shego, who were both suffering from colds, sneezed at the same time and said, "Bless you," before resuming the fight.
The Simpsons. Bart Simpson and Principal Skinner on several occasions. In a rather poignant early episode when Skinner was sacked, he and Bart actually become good friends. When Skinner rejoins the military Bart even admits to Lisa that he misses him as a friend but misses him even more as an enemy. After Bart helps Skinner become principal again they both realize their friendship can only continue if Bart becomes a good student — something they both know isn't going to happen.
Halfway invoked in Xiaolin Showdown after the monks team up with Jack Spicer in order to defeat Wuya. After they succeed Jack calls off the truce but Omi manages to guilt trip him (by using his Puppy-Dog Eyes) into offering to take everyone out for ice cream whenever they aren't fighting. The monks gladly accept the offer, but since they never actually stopped fighting, it never comes to fruition.
In Street Sharks, the Seaviates aren't above pulling harmless pranks on the Sharks when they're not trying to kick each others' fins.
Spildit often does this in The Dreamstone. While the Noops and the Urpneys mostly remain antagonistic towards each other throughout the show, Spildit, being a small child, often engages in friendly chat with Sgt Blob's team or even obliviously helps them in some of their schemes, which they usually seem rather nonchalent about.
My Little Pony: Friendship Is Magic, sort of. There are several cast posters floating around that depict the entire cast posing for a picture. Including villains like Discord.
This trope is also the premise of the episode Luna Eclipsed.
Finn and the Ice King in Adventure Time don't start this way - but once Finn and Jake find out that the Ice King is mentally ill, not evil, they begin spending social time with him. (Not much, because the Ice King is still very irritating company, and still needs to be stopped from doing something evil on a regular basis.)
Native American mythology in The Real Ghostbusters states that an ancient burial ground is the site of a war between the forces of good and evil. In "Night Game," the burial ground is now a minor-league baseball field, which means that Good and Evil are playing baseball. Things get...complicated...when Winston enters the fray.
Swiper the Fox has a friendly relationship with Dora and Boots when he isn't stealing something important from them, and they even organized a surprise birthday party for him in one episode. He's really only a villain insofar as he hinders them on whatever journey they take by making off with and hiding a few key items, which might go a long way towards explaining how they're on otherwise friendly terms.
Also from the First World War, the early airplane pilots were often pre-war flight pioneers, and knew each other from various contests and meetings and the like. Only after some time they began to greet the other guy with bullets instead of salute.
By the late 1980s it wasn't all that uncommon for former WWII soldiers from all sides to attend each others' reunions, perhaps because they had something in common with their former enemies (the shared experience of combat) that they couldn't share with the people back home.
Federal and Confederate soldiers both showed up to commemorate the anniversaries of Civil War battles at least as far as fifty years after war ended. This is something of a negative example, though, since black soldiers, who made up about 10% of the Union forces, were not welcome at those gatherings; basically, the white troops on both sides decided to forget what the war was about and dismiss the whole thing as a big misunderstanding.
General Joseph E. Johnston, the Confederate officer who led the troops opposed to Sherman's march, helped to carry Sherman's coffin at his funeral. The funeral was on a cold day and one of Johnston's friends told him to wear a hat, but he refused to out of respect for Sherman saying, "If I were in his place and he standing here in mine, he would not put on his hat." He got a cold that developed into pneumonia and died shortly thereafter.
In 1862 the Union troops and the Confederates ended up on different sides of the Rappahannock River in Virginia while the Northeners were waiting for supplies. It drew out, so the soldiers got gradually more bored. With little to do but to stare at each other, they began carving little toy boats and filled them with tobacco or coffee and sent them across to the enemy. Then they started greeting each other and waving. Then they crossed the river to have a friendly chat and exchange newspapers. Then the Battle of Fredericksburg ruined everything.
During the siege of Vicksburg, both sides agreed to a temporary truce (to recover the bodies of the fallen in the no-man's-land between the lines ... it was in Mississippi approaching summertime, which added a practical emphasis to the usual "respect for the dead" reasons). During the truce, soldiers on both sides intermingled and traded supplies with each other. I mean, sure it's supposed to be a siege, but not letting them have whiskey or tobacco would just be uncivilized.
During the Italian campaign of World War II, members of the British Parliament complained when it became known that Montgomery had invited a captured German general to dinner as a courtesy. Churchill, referencing Montgomery's well-known spartan lifestyle and tastes, replied that he had dined with Montgomery, and his sympathies were entirely with the German.
On the other hand, after the German surrender in Tunisia in 1943, some US officers suggested to general Eisenhower that he ought to invite his German counterpart to dinner as a courtesy. Eisenhower refused because he found the idea of nicely chatting with an enemy commander unappealing.
Following the sinking of the American Cruiser USS Indianapolis by the Imperial Japanese Submarine I-58, the Captain of the Indianapolis, Captain Charles B. McVay, was court martialed. The Captain of the submarine that sank his ship, Commander Mochitsura Hashimoto, testified at his court martial that Captain McVay's actions were not responsible for the sinking, and actually spearheaded post-war efforts to clear Captain McVay's name stating in a letter to Senator John W. Warner, then head of the Senate Armed Services Committee. "I have met many of your brave men who survived the sinking of the Indianapolis. I would like to join them in urging that your national legislature clear their captain's name." Unfortunately for McVay's reputation, even after a joint resolution from Congress, signed by then President Clinton in October 2000, and the US Navy admitting it screwed up, his record still retains the conviction for the loss of the Indianapolis.
The Cold War in general featured a whole bunch of this, since the two sides did not fight each other directly, and the United States and Soviet Union technically recognized and were at peace with each other. American and Soviet diplomats were frequently good — if careful — friends with one another, and most famously, Ronald Reagan and Mikhail Gorbachev struck up a friendship in the mid-1980s. The fact that this was true and not particularly well-hidden led some to speculate as early as the 1970s that a complete rapprochement between the US and USSR was in the offing. They were right—in 1989, Gorbachev officially stated that the United States was no longer a strategic enemy of the Soviet Union, and the USSR backed the US up politically in the Gulf War—but unfortunately for these prognosticators, the Soviet Republics decided to declare independence from the USSR one by one, until the Russian SFSR, the largest SSR, did so, leaving the Soviet Union a mere scrap of paper.
Uesugi Kenshin and Takeda Shingen, during the Sengoku Jidai in Japan, though it only happened once (if at all), and the rest of the time they only sent letters and exchanged valuable gifts while trying to outmaneuver one another in combat. At one time, Kenshin sent Shingen some much-needed salt (a valuable commodity in those days), expressing his chivalric opinion that "Wars are to be won with swords and spears, not with rice and salt." After Shingen's passing (which was mourned by Kenshin, who also refused to take the opportunity to attack, as his retainers urged him to) the two clans became allies against rising power Oda Nobunaga.
Due to the rules of chivalry, this happened fairly often as a knight was obligated to treat captured opponents with respect and even provide food, entertainment and lodgings like a guest. It helped that the captured enemy was often ransomed and the "hospitality" was added to the bill.
Though Saladin and Richard the Lionheart never met, it is told that they played correspondence chess via pigeons. While this story may or may not be true, it's telling about both of these men. War in general was not always particularly hostile and resembled a sport for the ones who didn't have to brave molten lead at the gates of an enemy city, and lords and generals on both sides of any conflict might as soon go hunting together as try to outsmart each other on the battlefield. Until the 19th century it was usually thought that war was just a part of diplomacy and politics.
Attorneys. Knowing it isn't personal, knowing the enemy of today might be the teammate or even coworker of tomorrow means that many attorneys will argue against each other all day, and then go get a drink after work. Actively encouraged by codes of conduct requiring civility.
The Olympic Games, both in their traditional, greek form and their more modern incarnation. Most notably the 1936 olympics, which were hosted by the Nazis.