Chance Meeting Between Antagonists

This trope is when the hero and the villain (or any two people at odds with each other) happen to cross paths, purely by coincidence. This might happen at some particularly dramatic moment, though this isn't always the case. Perhaps one of them made a mistake, or the other just got lucky, but in either case, the main point of this trope is that they are both surprised by the encounter.

For example, Alice may be infiltrating Bob's secret lair. She finagles her way past all the guards and security systems, finally making her way into Bob's inner chamber. Just as she cracks Bob's safe, filled with all his secrets... a toilet flushes in the adjoining room and Bob steps out zipping his fly, unaware that anything had been amiss. Until now, that is.

Another (and more likely) scenario is when the hero and villain simply happen to cross paths without either being consciously aware that the other would be present beforehand. In some cases, they may not even realize who they saw until sometime afterward, when someone else mentions them. Or it could be the Secret Identity is revealed and the hero had been Living with the Villain all along.

A subtrope of Contrived Coincidence. Also compare Villains Out Shopping, which is one of many possible setups for such an encounter.

Examples:

Anime & Manga
  • In Magical Girl Lyrical Nanoha A's, Team Nanoha (the heroes) accidentally meets Team Wolkenritter (the heroic antagonists) in a hospital while visiting the Wolkenritter's master Hayate (who also happens to be a friend of Nanoha's friend Suzuka; they didn't know she was their enemies' master until then, however). This takes place just before the Final Battle, so it doesn't go well at all.
  • This is a staple in the various Gundam series, with the heroes typically meeting their enemies by accident while out of their respective mechas and uniforms. For instance, in Mobile Suit Gundam SEED, Kira and Cagalli accidentally meet the enemy commander Andrew Waltfeld and his lover/partner while scouting an enemy town for supplies. That meeting ends rather amicably: even though Waltfeld immediately realizes he is dealing with enemy aces, he likes them well enough to let them go on that occasion.
  • Patlabor
    • In "The SVU's Longest Day pt.2" Asuma happens to see Kai, while he was waiting for Noa at a ramen noodle stall. It isn't until he sees Kai's picture during a news broadcast, hours later, that he realizes he'd seen the leader of the rebel army that was currently laying siege to Tokyo.
    • While, in the Mobile Police continuity, Noa and Asuma go to an arcade center on their day off and end up running into Richard Wong and Bado, who would later prove to be the series main antagonists during the Griffon arc.
  • In Heat Guy J, Daisuke is going to lay sunflowers on his father's grave, and meets up with Clair, who has just visited (and stomped on) his own father's grave. The two look at each other for several minutes, before walking past one another.

Film
  • Pulp Fiction: A boxer named Butch, on the run for not throwing a fight for Marcellus Wallace (a local crime boss), shows up at his apartment to retrieve his gold watch. He decides to have a quick snack...and notices a submachine gun lying on the counter and picks it up to examine it. Cue toilet flush, and Vince Vega (who works as muscle for Wallace) walks into the kitchen, finding Butch with his gun. Exit Vega.
    • The next scene: Butch is driving back to the hotel he and his girlfriend are hiding out. He stops at a light, and who should cross the street at that exact moment but Marcellus Wallace, the man who put the hit out on him, who was out getting coffee.
  • In The Town, the Villain Protagonists have just pulled off a daring robbery and managed to escape pursuit... only to run smack into a police officer while they switch cars. The officer chooses to pretend he didn't see them.
  • In Superman Returns, Lois sneaks onto Lex's yacht (not knowing it's his) and runs into the man himself, while he is brushing his teeth and utterly surprised to see her there.
  • In Kick-Ass, after having his operations foiled, the Big Bad puts a hit out on the eponymous hero. Then, as he's casually driving down the street in his limo, who should walk past but Kick-Ass! Actually a subversion. It was really an unfortunate Kick-Ass imitator, whom the Big Bad shoots in the head and then inspires the real Kick-Ass to retire in fear of his safety.
  • Captain America: The First Avenger: While searching for Bucky, Cap happens to spot Dr. Zola fleeing his lab, but abandons pursuing him in favor of finding Bucky. A few minutes later, however, the two encounter Schimdt and Zola as they all head for the elevator, and Zola ends up cutting them off so that the heroes can't reach them.
  • In Batman Returns, Bruce Wayne and Selina Kyle are at the same party when they realize that they are enemies (i.e., Selina figures out that Bruce is Batman, and he that she is Catwoman) while they dance together.

Literature
  • In A Song of Ice and Fire, two characters travelling in opposite directions, going on about their own business (Catelyn Stark and Tyrion), recognise each other in an inn, causing the intrigues of other characters to spiral out of control into an all-out civil war.
  • In Soon I Will Be Invincible, Dr Impossible is having a cup of coffee and reading the paper when several members of the New Champions run across him and a battle ensues.

Live-Action Television
  • In Burn Notice, Michael is infiltrating a bomb-maker's apartment. The bomb-maker had rigged a booby-trap to the door: a claymore, pointing at the door, tied to a rope. If the door opens, the rope slackens, which will set off the claymore. Michael, luckily, notices the trap and pulls on the rope to keep it taut. At that exact moment, though, the bomb-maker happens to walk in the back door. Though surprised, he quickly takes advantage of the situation, since Michael is standing directly in the path of the claymore and can't let go of the rope.
  • Firefly: The episode "Trash" has Mal run into Saffron his ex-wife, who tried to get him and his crew killed on some backwater moon. As soon as they see each other they draw guns on each other.
  • Breaking Bad: Walt happens to meet Jane's father Donald Margolis the night she dies. He later talks with Jesse after he realizes what happened about the "astronomical" odds of the meeting.
  • The 100: When Clarke checks out the forbidden areas of Mount Weather, she discovers Anya, last seen trying to kill Clarke and all her friends, locked up in a cage.
  • Hannibal: During season 3's "Red Dragon" arc, the first significant divergence from the novel's plot happens when the killer Francis Dolarhyde, who has conned his way into the Brooklyn Museum to destroy the William Blake painting, is interrupted by Will Graham, the man in charge of catching him, who was tipped off to the painting's importance by Hannibal.

Tabletop Games
  • One War Zone battle scenario works like this, pitting two scout teams (the Bauhaus and Mishima) against each other. The scenario starts with the sergeants of both sides already dead; both scout teams have been crawling through tall grass and somehow Failed a Spot Check until the leaders nearly bumped into each other.

Video Games
  • In Tales of the Abyss, there is a scene where the protagonists are going to visit a scholar who have knowledge pertinent to their quest. When they arrive, the Big Bad is already there, reading up about the same subject. The two of them have a bit of a row, but out of respect for the scholar (an old friend of his), the Big Bad leaves without anything coming of it.
  • In one sidequest in Final Fantasy VII, Cloud and the gang pursue Yuffie to Wutai after she steals all of their Materia, where they find several members of the Turks hanging out in a bar. Fortunately, the Turks are currently on leave and aren't interested in pursuing their conflict with Cloud.