When two or more people team up to achieve a goal, it's generally assumed that their goals are reasonably similar. At the very least, what one of them wants to achieve shouldn't conflict with what the others want to achieve. Otherwise, why would they team up?
Because they didn't know what their teammates are after.
Maybe someone lied to them (see Not-So-Well-Intentioned Extremist for one such case), or maybe they just never discussed the plan in enough detail to know their allies' true goals. Then again, they may have started with the same general goal and one (or more) of the teammates has slipped in their ethical standards and is willing to cross any lines to achieve it. In any case, it's only when their long, elaborate plan is nearing completion that they finally discover what they've been working toward all this time (and how they mean to finally get it). Their reaction is inevitably, "Whoa, I didn't sign on for that!" Can result in Screw This, I'm Outta Here.
Compare Dragon with an Agenda, Not in This for Your Revolution, Mistreatment-Induced Betrayal and Right Hand Versus Left Hand. May lead to an Enemy Civil War. Even Evil Has Standards can be a cause. May overlap with Not in My Contract if specific agreements are invoked in detail to justify breaking off the agreement.
See also You're Insane!
- Bone: The Pawan leader is fine with working with the Hooded One and the Rat Creatures at first, but after it becomes clear to him that the Hooded One is going to literally destroy the Valley, he takes a stand. Unfortunately for him, the Hooded One would rather just slice his head in two and give his second-in-command a Klingon Promotion than argue ethics with him.
- During the Civil War, Spider-Man is initially in favor of the Superhuman Registration Act, going so far as to reveal his Secret Identity on national television. However, when he discovers that Iron Man's pro-registration faction is imprisoning the non-registered supers they capture in a specially-made prison in the Negative Zone without even a trial, he promptly defects to Captain America's side in disgust.
- Robin (1993): A teleporting supervillain named Dodge put together a team of fellow bad guys to avenge himself on Robin. He was doing well right up until he found The Cheater electrocuting Robin, at which point it was revealed that while (almost) all his minions were in it for murder, the leader himself was way out of his depth — he just wanted to humiliate his enemy. Then they decided that a teleporter was far too useful to allow to quit.
- Sonic the Hedgehog (Archie Comics): In the "Mobius: 30 Years Later" storyline, the Dark Presence frees King Shadow in order to restore him to the throne. When they find out that Shadow actually plans to release Tikhaos, they flee, even quoting the trope name word-for-word.
- In the Superman storyline Last Daughter of Krypton, Jacobs, a mercenary hired by Simon Tycho, had no qualms about working for his shady boss until Tycho captured Supergirl and expressed openly and casually his intention to dissect her. Deciding he was not hired to help torture innocent girls, Jacobs frees Supergirl from her containment pod, and gets gunned down by his own boss straight after.
Jacobs: This isn't what I signed up for, Miss. I thought Mr. Tycho was a genius. Thought he was gonna help the world. Not torture innocent people.
- In Trinity War, most of the JLA does not want to fight the Justice League, no matter what Batman says, and think they should be supporting them.
- In X-Men Age of Apocalypse, Sabretooth is an X-Man. In his backstory, he revolted when he learned that Apocalypse hired him for a much more lethal plan than he had realized, and he regards this as atonement.
- The specialist team of Atlantis: The Lost Empire may be mercenaries Only in It for the Money, but they do have some standards. When Rourke takes the Heart of Atlantis, effectively condemning the entire city to death, the whole lot of them defect.
Vinny: We done a lot of things we're not proud of. Robbin' graves, plunderin' tombs, double parkin'... But hey, nobody got hurt. Well, maybe someone got hurt, but nobody we knew.
- In Big Hero 6, when Hiro removes Baymax's caregiver programming and tries to have him kill Callaghan in revenge for his brother's death, his allies call him on it.
Wasabi: What you just did, we never signed up for.
- In Catwoman: Hunted, Batwoman and Selina gatecrash a meeting of supervillains who, after seeing our heroes wipe the floor with their mooks, summon monsters and demons to take them on.
Catwoman: I...did not sign up for this. (beat) Did you sign up for this?Batwoman: Uhhh...um...Catwoman: You really have to think about that?Mook: (terrified) I definitely did not sign up for this!Catwoman: See? Even he knows.
- In The Powerpuff Girls Movie, Mojo Jojo persuades the girls to use their powers to build his "Help the Town and Make It a Better Place Machine" — which, it turns out, is actually a device to allow Mojo to create his own army of primates powered by Chemical X.
Blossom: Jojo, what happened?!
Bubbles: This isn't making the town a better place!
Mojo Jojo: Yes, it is ... for me!
"He ain't just after money, you know."
- In Hogfather, Mr. Teatime hires several Mooks to help him kill the Hogfather (Discworld's version of Santa Claus). It's not until near the end of the book that Teatime reveals that this is what all their elaborate plans were for. One of the Mooks, despite being a thug and murderer, does not take kindly to the idea of eliminating their universe's version of Christmas and turns on Mr. Teatime. Even before that, there was grumbling:
"Yeah, well, I didn't sign up for world domination. That kind of stuff gets you into trouble."
- In Making Money, Moist declares he didn't sign up for running a bank. Vetinari replies that what Moist "signed up" for was being hanged, and he's only still alive because Vetinari saw use in him.
- In The Ear, the Eye and the Arm, the She-Elephant feels this way after learning the Masks are intending to kill the Matsika children, as opposed to simply indoctrinating them into their gang.
- Harry Potter:
- As revealed in Harry Potter and the Deathly Hallows, Regulus Black pulled a Heel–Face Turn when he discovered Voldemort's plans. Subjugating Muggles and mudbloods was fine. Tearing apart one's own soul in a bid for immortality? Not so much. That could also have something to do with Voldemort's treatment of Kreacher.
- In Order of the Phoenix, Sirius mentions that there were a number of Old Name families like his own who initially thought that Voldemort had the right idea, but then quickly changed their minds about him when they saw how far he was willing to go for Pureblood Supremacy.
- Mundungus Fletcher does one of these as well, except he really never did sign on to die for Harry, as he tells him.
- The Malfoys seem to have some major regrets about joining up with Voldemort by the final book, to the point where Draco refuses to firmly say whether it's really Harry or not when he's captured by the Death Eaters and Narcissa and Lucius lie and tell Voldemort Harry is dead, and then refuse to fight in the subsequent fracas because they know it means they will be reunited with their son.
- A rare non-heroic example from Chamber of Secrets: Gilderoy Lockhart joined up to the Defense of the Dark Arts teaching profession at Hogwarts. However, when he discovered that a girl was kidnapped, he attempted to flee, and implies that he's doing so because "saving students was not part of the job description." It's all the more unheroic because it WAS his job as a teacher at Hogwarts to protect the students, especially as the combat specialist.
- The Hearts We Sold: Cora and James argue this when they discover the Daemon is having the heartless troop fight monsters to prevent The End of the World as We Know It, and that there's no guarantee any of them will make it. The Daemon shuts them up by pointing out that, yes, they did sign up for this — though he didn't tell them what they were getting into, he never forced anyone to make a bargain with him, and he made it clear he expected two years of labor out of all of his charges. He also points out that a lot is riding on it, much more than their own personal safety, and that, furthermore, he's paying them all extremely well for their time. Dee concedes that he's not wrong, though she's still as pissed as everyone else that he didn't tell them upfront what the deal was.
- Moby-Dick: Starbuck is on the Pequod to hunt whales for business, not assist his captain in his mad obsession for one specific whale that obviously wants to be left alone. He certainly thinks this, and in some adaptations voices this very phrase. Only his sense of duty keeps him from mutinying.
- In Rainbow Six, the ex-KGB agent hired by the Strawman Political environmentalists to provoke terrorist attacks does a Heel–Face Turn after discovering that their ultimate goal is killing off most of humanity.
- The Stormlight Archive: When the Parshendi killed the Alethi king and retreated to the Shattered Plains, the Alethi declared a war of vengeance on them. Countless young men joined up, determined to show the world that the Alethi would not stand for treachery. Unfortunately, due to the nature of the Shattered Plains, the Parshendi had a massive advantage over the Alethi, so the Alethi chose to lay siege rather than performing a suicidal assault. Then they discovered that chasmfiends like to pupate on the Plains, and each chasmfiend has a massive gemheart, enough to pay for an army for months. The Parshendi need them as well to feed their own army, so they skirmish over them. It doesn't take long before the Alethi have forgotten vengeance, and are instead just fighting for money. Since the wartime military oaths mean the soldiers can't legally leave, many desert and become bandits prowling the Unclaimed Hills west of the Shattered Plains.
- Daredevil (2015): Ray Nadeem finds out that Wilson Fisk has managed to blackmail all of the FBI agents protecting him into working for him (with the exception of Dex, who was manipulated). Nadeem is forced to work with Dex to do Fisk's bidding. When Dex is tasked by Fisk with killing Karen as revenge for her killing James Wesley, Nadeem is the one to drive him there. After Dex's attempt fails and they return to the church in their capacity as FBI officials to smoke out Matt and Karen. While entering the church, Nadeem notices that Dex had killed Father Lantom during the attack and expresses his disapproval of Dex's actions.
Ray Nadeem: I did not sign up for this shit!
Benjamin "Dex" Poindexter: Yes you did...
- Firefly: In the second episode "The Train Job," the crew of Serenity take a job to steal supplies from a train by vicious crime lord Adelai Niska. However, when Mal and Zoe discover that the supplies are badly needed medicine for a degenerative disease, they back out of it, return Niska's money to his henchmen, and deliver the medicine to the town where its needed.
- General Hospital: During the 2005 storyline in which A.J. kidnapped Sonny's children as part of his latest scheme to get Michael back, his father Alan is sympathetic and initially tries to help him, only to turn him in to the police when he see that A.J. is perfectly willing to use violence to get what he wants. In turn, A.J. shoots him in the back and leaves him wheelchair-bound.
- In Lost, after witnessing why Keamy's mercenary team was really sent to the Island, their fellow freighter passenger Miles almost quotes the trope name verbatim.
- Occasionally, the guest star on The Muppet Show will find themselves objecting to whatever weird sketch or piece The Muppets have cooked up for them.
- In Smallville's Vengeance Chronicles Andrea Rojas teams with Molly Griggs and Nick Yang. She realized that their plan to stop Level 33.1 was to have Molly send Lex Luthor a hypnotic message to kill himself rather than expose the project. Since Lex is protected by Joker Immunity, she invokes the trope.
- Throughout Star Trek, Starfleeters frequently run into the weirdest things that can be found in space, whether it's a Negative Space Wedgie, Timey-Wimey Ball, Sufficiently Advanced Alien, Mirror Universe, or whatever else one can think of; they've Seen It All and then some, and sometimes actively seek such things out just for fun. As such, whenever an outsider (such as Kira Nerys or Neelix) ends up on one of their crazier rides, expect complaints about how they didn't sign up for this.
- The pilot episode of Star Trek: Picard features a variation, with Picard angrily declaring that he resigned from Starfleet "Because it was no longer Starfleet!" (after the Federation abandoned the population of the Romulan home system to its fate in response to political pressure).
- In Dawn of a New Age: Oldport Blues, Daigo's gang of delinquents starts to fracture after he gains superpowers and starts taking his rebellious actions to murderous levels. Destiny objects outright and cuts ties to the gang; Marko distances himself from them after Daigo breaks a promise to not let his newfound power get to his head; Jae goes along with Daigo until he plans to put a bomb in the school, causing her to break off in order to warn her friend; and Kev is only still with the gang because he's too cowardly to put his foot down.
- The fake sea captain from Double Homework is okay with keeping the ship out of port, citing a bogus “international sea law,” but threatening him physically is enough to get him to surrender immediately, since he doesn’t think he’s being paid enough to fight back.
- Averted with the title character's tutoring lessons in Melody. After the success of the first week, Amy enlists the protagonist to check up on Melody periodically like Amy herself would do, and he agrees. Sure enough, in the second week, he has to care for a sick Melody.
- Five years before the start of the series, Ghira Belladonna, leader of the White Fang, was deposed by a coup, transforming White Fang into a militant organisation under the command of Sienna Khan, willing to use violence to achieve Faunus equality by force where peaceful protest is failing. Although the Belladonna family leaves the organisation, Ghira's daughter Blake remains, supporting the coup's new approach. However, under Adam's command, Blake finds the militancy becoming more violent and indiscriminate until Adam's lack of concern for the safety of innocents on a Dust train he wants to blow up becomes the line she cannot cross. Abandoning Adam and the White Fang, Blake goes on the run and joins Beacon Academy, hoping to achieve her desire for a better, more equal, world in a more honorable way. When Blake and Adam confront each other during the Battle of Beacon, she is horrified to learn that Adam has never wanted Faunus equality: he wants humanity defeated and broken, their fate to serve the Faunus.
- In Volume 8, Emerald, Mercury, and Hazel are horrified when they discover what Salem's true endgame is. They believed that she planned to simply Take Over the World, and are taken aback to discover from Ozpin that she actually plans to destroy Remnant outright; Emerald and Mercury are further horrified by the realization that Tyrian has known all along and actively supports it.
- Played for Laughs in Cassiopeia Quinn, when Theira grumbles that she signed on with the Prime Galactic Navy to shoot big guns, not file paperwork.
- Manly Guys Doing Manly Things: A Big Daddy signs on as a day care worker. He's really, really good at it. Problem: Nobody told him that at the end of the day, the kids have to go home. Trouble ensues.
- Happens in Sluggy Freelance when Mafiya boss Noah Zark reveals his plan to help animals by wiping out humanity.
Noah Zark: I will use your telecommunications satellites to broadcast my signal all over the vorld! Destroying humanity so zat only my beloved animals vill remain!
Zoe: You're mad!
Yuri: Ve are not mad! Ve just love animals! Ven humanity ees destroyed, only ve vill be left to eat ze tasty animals! Boy do ve love eatink tasty animals.
Noah Zark: Ve'll talk later, Yuri.
- Stand Still, Stay Silent: In the Distant Prologue set Just Before the End, Árni Reynisson joined the coast guard only to see its duties turn into enforcing Quarantine with Extreme Prejudice. He tries Just Following Orders for a while, but ultimately answers to the Call to Agriculture.
- Unsounded: Bastion gets upset when Bell has the town of Ethelmik razed to hide their transport of First Silver, then yells at Prakhuta that he signed on for a rebellion against corruption not genocide. Prakhuta points out that Bastion likes to act all high and mighty because he's upset after killing people, but Bastion is a murderer plenty of times over, has created his own Tortured Monster and treats war like a game so he's a hypocrite.
- The premise of the webcomic Watchdogs hinges on this trope. An honest man living in a city overrun by crime and vice is sick of living in fear and wants to fight back, Batman-style. He finds a neighbor with similar ideal and access to the necessary gadgets, and they become vigilantes. Soon after, the man finds out that his partner is actually a white supremacist and wants to use their team to attack minorities. When confronted, the neighbor's excuse is that he forgot to tell his partner he was racist.
- The guys at CinemaSins must hate this line, especially when it's used by someone who should have expected whatever is happening. The result is them mocking this trope on several occasions; for example, they respond to the example from Avatar with "You fly a military helicopter and you didn't sign up for this shit?!" and the one from The Dark Knight gets "Really?! You are a SWAT officer!!"
- It is rare, but not unknown, for serving soldiers to desert rather than fight, quoting this very reason for their refusal.
- An example would be Lance-Bombardier Victor Williams of the Royal Artillery, who in 1991 deserted on grounds of conscience rather than fight in Iraq.
- There is also a story of an Irish-born soldier in the Parachute Regiment, who had a crisis of loyalty on a tour of duty in Northern Ireland. In the aftermath of the killings of Bloody Sunday,note this individual is said to have deserted with a rifle and lots of ammunition and defected to the Provisional IRA.
- In the Canadian and US Military services at least, this is a legal defense for refusing to obey orders, but it's not so much desertion as it is your duty to do so under specific circumstances. If your commanding officer is ordering you to commit an unlawful order like a war crime, you are actually legally bound to be able to recognize it as such, refuse to do it, and do everything in your power to prevent it from happening. Either way you'd better be able to defend your actions during a court martial.
- When George Atzerodt, one of John Wilkes Booth's accomplices, agreed to help him, he thought the plan was only to kidnap Abraham Lincoln (which admittedly had been Booth's original plan). Atzerodt only learned the true plan — to simultaneously assassinate Lincoln, Vice President Andrew Johnson, and the Secretary of State — on the day it was to be carried out. Atzerodt told Booth this wasn't what he'd signed up for, but Booth told him it was too late for him to back out. Instead of attempting to assassinate VP Johnson as he was supposed to, Atzerodt went out and got drunk instead, though he was still arrested and hanged as a co-conspirator.
- The Saint Patrick Battalion, during the Mexican War. The Battalion was formed by a group of disgruntled Irishmen, though men from other countries joined as well by the war's end. The leader was a naturalized US citizen, who was perfectly gung-ho about conquering Texas and California for the US. But he was also a Catholic, and he drew the line at raping nuns and pillaging missions. In addition, he was disgusted by how the US soldiers treated the Mexican civilians in general. He and many others of those who survived the war, and many who claimed to have fought in the Battalion, lived the rest of their lives in Mexico.