Revy: No problem. Once the fighting begins, our instincts will take over and that’ll be it. No preparation necessary. It’s just how we’re made.
Sometimes preceded by a Face, Nod, Action, badass instincts requires two badasses to cooperate perfectly without a plan or full communication. They are not a Hive Mind and they can’t read each other’s minds. They are just that badass. To be invoked it must be made obvious that there is no way that the characters involved would have the opportunity to devise a plan for the situation but come out on top despite this due to perfect cooperation. In order for Back-to-Back Badasses to qualify there must be significant interaction between the two like using the partner as a weapon or jumping platform without requesting any assistance.
- Black Lagoon: The quote above comes from when Ginji and Revy assault a bowling alley filled with armed thugs. The relationship between Ginji and Revy could be described as strained at best and further hampered by a complete Language Barrier that prevents any planning. Despite this they cover each other on multiple instances in the following fight instinctively. This cooperation is possible because, as Revy puts it, both she and Ginji are just that Badass. Revy also does this with Mr. Chang, which makes more sense, as he trained her.
- Eureka Seven: When Eureka and Renton pilot their side by side mech they are able to move it without any communication between due to the power of love.
- Gunsmith Cats: Minnie May’s escape from Radinov’s car. The titular pair practiced syncing up head nods to music at the beginning of the episode. Other uses for synchronized head moving is an infallible escape timer which was communicated with flashing high beams in time to the music which cued May to use the hidden explosives that Radinov must have missed in the frisking to frame the rear window without Radinov noticing and at the climax of the song blow up the window and jump out and onto Rally’s waiting car hood through gunfire while running a red light and speeding!
- A mostly non-action version in Moriarty the Patriot between William and Sherlock: when they solve mysteries together, they come to the exact same conclusions independently of each other and handle each side of their task without prior planning. They also do this in The Adventure of the One Student when getting Bill his place at Durham University. And in The Two Criminals, they both shift to point their guns at Milverton simultaneously.
- One Piece: When Luffy and Zoro first meet Luffy has freed him from captivity at the hands of Navy captain "Axe-Hand" Morgan and they're pitted against Morgan and his marines. Morgan's son Helmeppo attempts to take Luffy's friend Koby hostage to stop him attacking Morgan. Luffy doesn't hesitate to launch an attack at Helmeppo to save Koby, despite this leaving him wide open to attack by Morgan. The attack goes nowhere, however, because Zoro steps in to stop the attack by bringing down Morgan. Luffy had full faith in Zoro doing his part despite having only just met him and seen him in action.
- Rebuild World: Akira and Token Evil Teammate Nelia, which is also Strange Minds Think Alike because they both have a sort of Blue-and-Orange Morality. That, and the shared beliefs of valuing I Gave My Word to a high degree and being a Consummate Professional all serve to be Commonality Connection between the two. They coordinate perfectly in battle as a Short Range Girl Long Range Guy duo with Akira maneuvering to Draw Aggro and staggering foes to create openings. Nelia would say it's because they're soulmates.
- Tengen Toppa Gurren Lagann This seems to be how the two cockpits for the titlular mecha function. A screen was placed inside so that they could see and communicate, but most fights are so hectic it's unlikely they can (or even wanted to) form a plan. And their mecha is the one that ends up with the highest kill count at the end of every episode...
- In Cave Story Versus I M Meen, Jack learns the ability to summon King's spirit from the blade, and the results during the final battle are absolutely spectacular.
- In the Command & Conquer/Mass Effect crossover fanfic Renegade, Garrus and Admiral Havoc both come up with a plan to raid a mercenary group's hideout by essentially busting down the front door and charging in with a few dozen troops and kill everything in sight. Shepard convinces them to back down and keep the troops in reserve, and instead leads an infiltration team inside the building. Then Zaeed Massani shows up and does the exact same thing Garrus and Havoc were planning, except in this case he's doing it by himself with a Mini-Mecha.
- The Boondock Saints and the sequel All Saints Day displays on multiple occasions that the MacManus brothers specifically rely on this in combat. Specifically their responses when attacked by Il Duce, or when they fell through the air duct are generally played out symmetrically.
- In Captain America: Civil War, even though the last time Cap and Bucky fought together, Bucky wasn't a Super-Soldier let alone a recovering former HYDRA killing machine, they make a perfect team fighting their way through the UN mooks who've come to arrest Bucky for Zemo's False Flag Operation. It's only the Black Panther's interference that eventually gets all three of them arrested.
- Mr. & Mrs. Smith (2005): The title characters demonstrate this for the entire final act of the movie. One particularly outrageous example is when Mr. Smith fires a shotgun that is still slung across Mrs. Smith's back.
- The Other Guys do this in the office scene after all the guns are drawn, detective Gamble throws a stack of paper into the air and Hoitz engages the attackers despite how this contradicts the initial plan to be discreet.
- At the end of Pirates of the Caribbean: The Curse of the Black Pearl, Jack and Will display this, particularly during the rescue where the two work in perfect harmony to take out the soldiers without having had any time to plan whatsoever.
- Rush Hour 3 does this during the hospital shootout when Lee gives Carter an empty gun without realizing it and decides the best way to load Carter’s gun would be to grab the magazine, slide toward Carter on a mail cart and push the magazine into Carter’s gun so he can use it. Also, immediately afterword, when interrogating the French Asian, Carter asks Lee for his gun and attempts to execute the man only to find there are, again, no bullets in it. This luckily leads to their captive taking them seriously when they threaten to kill him a second time so he reveals a key piece of information.
- The Angel episode, "Double Or Nothing," when the team goes to save Gunn Just in Time, Angel gambles his soul to keep Gunn from losing his. He gives Cordelia a stake, saying "you know what to do," implying that he means that should he lose his soul, she must stake him. When he loses the game, she immediately stakes the demon, allowing Angel enough time to cut his head. It doesn't kill him.
- In the Stargate Atlantis episode "Midway", Ronon Dex meets THE original Proud Warrior Race Guy, Teal'c. The two spend the first third of episode giving each other the hairy eyeball and smacking each other around. When they reach the titular space station, they run afoul of a Wraith invasion force working it's way to Earth. Without any possible warning or planning, the two of them start kicking shit out of the Wraith, climaxing with them halting their invasion of the SGC.
- One Star Trek: The Next Generation episode involves the bridge crew of the Enterprise working together to trap an alien who appeared on the bridge without the crew communicating with each other. Captain Picard mentions to the alien that the crew knew what he would order without him having to do so because of their good working relationship.
- Sybella and Beast in the final battle of Dark Triumph. Despite Beast showing up unexpectedly at the last minute and having no idea how much trouble Sybella was in before he appeared, he and Sybella fight together as a unit and manage to escape from the bad guy into a river.
- Red Panda Adventures: The climax of the novel The Crime Cabal features Constable Andy Parker watching in amazement as the Red Panda and the Flying Squirrel battle a small army of mooks with a coordination that beggars belief. Despite having come into the Crime Cabal's lair to rescue the Squirrel, the moment she arrives on the battlefield, having escaped on her own terms, she and the Red Panda immediately launch into a coordinated maneuver in which he spins her around to take out several opponents at once. They then proceed to fight as Back-to-Back Badasses, watching one anothers' back and always being able to move or dodge at the precise moment the other hits a mook with an attack that would otherwise have hit them.
- Professional Wrestling matches are usually performed on the fly — the opening, ending, and a few high spots are planned but the rest is done spur-of-the-moment as it feels best to the wrestlers involved.
- The plan in Call of Duty: Black Ops at the beginning of the level "rat tunnels" certainly qualifies. When the player and their companion is being forced to play Russian roulette and it is their turn the ally gives a verbal equivalent of the head nod, "This time, this time," and the player follows it up with saying "6 and 8 o'clock". What follows after this is a complex process of gun stealing, human shields and action diving that results in the majority of the other people in the room getting killed.
- Averted in Metal Gear Solid 4, where the Rat Patrol's nanomachines let each member of the squad see and hear what each other member is seeing and hearing. This allows them to pull off maneuvers with ridiculous precision and coordination. Then it's played straight when Meryl teams up with Johnny Sasaki who doesn't have nanomachines.
- Tales of Vesperia. Flynn's in prison in Dahngrest, and Yuri comes to visit him. Not only does Flynn figure out who it is by the sound of Yuri's footsteps, but also, in the middle of a conversation about who might have set Flynn up, Yuri unexpectedly opens the prison door to let Flynn out. Flynn's reaction?
Flynn: I was wondering how long it'd take you to get rid of that damn lock.
- In the Avatar: The Last Airbender episode "The Blue Spirit", Aang and the title spirit cooperate instinctively to fight their way out of the prison where he was being held, all without the Blue Spirit saying a single word. This takes a turn for the awkward when the spirit turns out to be Zuko.
- Miraculous Ladybug: Ladybug and Cat Noir are usually able coordinate perfectly with only minimal communication.
- CQB training ingrains a specific response for every possible situation which allows all members of the team to know exactly what everyone else is doing. Of course, this may instead be better filed under Crazy-Prepared.
- This video starting at around 2:00 in.
- An efficient military system is like this. If each unit commander knows his mission and can be trusted to carry it out both loyally and competently the operation has more chance.
- In the German army for instance, it used to be traditional to give the commander of a column a "mission order" telling his objective, and then make no further interference, other than occasional progress reports, until the mission is fulfilled, aborted, or changed.
- There is a movement in the United States Armed Forces, originating from the Marine Corps to introduce "Strategic Corporals". In other words, much like the German army above, the thought is that in a world of increasingly unconventional warfare, you need even your lowest ranked grunts to be able to work independently on their own and with each other in situations where calling up The Cavalry on the horn may not be possible or feasible.
- The Canadians' ballsy victory at Vimy Ridge was based on this trope in action.