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Just For Fun / How to Stop the Deus ex Machina

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Fridge Logic is a cruel mistress and a deadly force. It can destroy Willing Suspension of Disbelief in seconds, as a viewer realizes the heroes (or villains) could easily and quickly succeed if they took a certain action within their power.

So why don't they? Why did the author feel the need to have them do things the hard way? Often it's done to preserve the drama and sense of urgency in the plot, because there would be no story, or story worth telling, if they solved their problem easily.

If the author knows what they're doing, they'll take pains to point out why the heroes (or villains) cannot or will not take that step. Stopping the Deus ex Machina can be simple or complex, and may deal with physical limitations or mental, emotional, or moral ones (even technically laudable ones, such as "refuses to take a life" — though in practice that's not such a good thing all the time).

The most basic way of implementing these restrictions are Internal and External means. Internal restrictions are ones inherent to a character (personality, morality, skills, talent) and those that are self-imposed, like vows to help others, not kill, that sort of thing. External restrictions are ones that the environment imposes on the characters, be it in material restrictions or injuries. They might have their means of travel restricted, communications cut off, equipment damaged or disabled. Or they may be wheelchair bound, have a broken arm, a Power Limiter or reality itself somehow disallows an action, among other possibilities.

As you can see, though this guide has Deus ex Machina in the name, it covers situations that completely normal people could solve. For your reading convenience, they have been divided into topic sections covering how to stop characters from doing specific things, as well as specific types of impediments.

Mind over Manners is a subtrope.

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    Don't do that! 
  • How To Keep Your Hero From Just Walking Away
    • Internal: Give them a sense of obligation or indebtedness, or some other emotional reason to stay. If they're helped by a Good Samaritan, fall for a soiled dove, or any other Love Interest, or the antagonist makes it personal are all good reasons (note that if they are staying to help, you need to give the person being helped a reason to stay, too, so we don't ask why the hero didn't just bring them along while he left).
      • Example: In Silent Hill, the protagonist Harry wouldn't leave even if he could since his daughter Cheryl is lost in the monster-filled town.
    • External: Make it impossible for them to leave by putting them in a Closed Circle, or making it worth their while to stay. Like having someone offer them money, or putting them in house arrest so that leaving is undesirable.
      • Example: In the original House on Haunted Hill (1959) and its remake, the mansion has deadbolts, iron reinforced windows, and all are on a time lock. No one gets out before the party is over.
  • How To Maintain Lack Of Communication
    • Internal: Mistrusting other characters (with reasons to not trust them!); Being Watched or some other surveillance.
      • Example: In Ranma ½, both Ranma and Akane are too stubborn to honestly admit their romantic feelings for each other, and prone to (almost willfully) misreading situations to think the worst of each other.
    • External: Aside from mundane and personal reasons, there are magical ones. A curse that makes it so they Cannot Spit It Out, or makes them entirely unable to speak. Faulty telephones, a loud environment, and having one or both gagged or deafened can also work for a time.
      • Example: In the fable of The Six Swans or The Swan Brothers, the only way their sister can cure them of their transformation into swans is to weave them sweaters while being completely silent. This leads the prince who loves her into being susceptible to her wicked stepmother convincing him she doesn't love him.
  • How To Keep Someone From Using His Awesome Powers
    • Internal: Self imposed limits to avoid collateral damage are also workable. Of course, the Godzilla Threshold will still have to be crossed at one point. Authors should not cheat viewers of a gun demonstration after showing them Chekhov's Gun.
    • External: This includes advice for justifying the Mentor's refusal to do the job himself, since he obviously has greater power than the rest of the cast. Having the environment be an Anti-Magic, or an enemy so powerful they can ignore the hero's powers. Or hire a person who specializes in it and let him do whatever he wants. For a climactic battle, consider setting up an environment that requires the full use of said powers just to function normally (and show what happens to normal people).
      • Example: Several episodes of Buffy the Vampire Slayer create a lot of anxiety by removing her powers, such as being hypnotized into thinking she's a Victorian lady, drugged into losing her super strength, or pinned under a chandelier.
  • How to rein in errant Phlebotinum.

    General Internal Limitations 
Aside from these specific topics, there are a lot of general Internal limits a hero or villain can self impose. Something they voluntarily choose not to do, or do in a certain way. This can work remarkably well both as a tool for characterization and a plot complication. However, you should take care not to make the restriction come out of the blue or be ridiculous. It's one thing for a hero to refuse to kill out of regret for having accidentally killed a friend in anger, it's another entirely for them to give some half baked excuse not to off the Omnicidal Maniac who's Made of Evil 'just because'.

But what happens when the Antihero or Card-Carrying Villain show up? These types do not play by the rules... except they do. Their own rules, that is. As The Unfettered, both may refuse to bow to the same constraints as normal people do, but that does not mean they are without some guiding intelligence and under some consideration. Be they an Übermensch, stylish villain or gritty loner, they are by no means exempt from Internal constraints.

Here are a few common ways for heroes and villains limit themselves.

Moral and Emotional:

Personality and Character:

  • Heroes: Even antiheroes who are fine with killing probably require some kind of prompt to do so, like a villain crossing the Moral Event Horizon or a personal threshold. A villain who is wise to these may well skirt "over" the hero's radar to avoid this treatment, or manipulate the hero into facing enemies he will not willingly harm. Providing said heroes with a Morality Pet (and the hero with a reason to listen to their pet) applies here as well.
  • Villains: If the villain is an Omnicidal Maniac with a bad sense of humor, or even a Serial Killer, their actions will be informed by their manias. Maybe they have Complexity Addiction and refuse to do evil acts without flair or 'just because', or their mental disorder (sometimes both are one and the same) mandates they can only kill people whose name ends with S on Tuesday, not Wednesday. Then again, a Lawful Evil villain may not want to compromise their standards ("morals" is a bit too strong a word here).
    • Villain who are prone to this: Noble Demon.
    • Example: The Riddler is obsessed with leaving clues at his crimes, first as a boast and then as a mental disorder. He literally couldn't avoid leaving a clue. He also couldn't reveal the identity of the Batman after he learned it, because a riddle that everyone knew the answer to is useless.

Physical and Mental:

  • Mental: Heroes or villains may be further constrained from taking an action by, put bluntly, not thinking of it. They might not be that bright, or their personality (see above) isn't an observant or creative one. Or if they are book smart, they aren't clever or deductive, so they put the clues together or come up with a foolproof plan. Then again, a clever, fly-by-the-seat-of-my-pants type might be too much of The Ditz to use their short term genius to problems that aren't immediate, or a meticulous Chessmaster can't predict the unpredictable. Other sure fire ways of doing this are to give them a distraction: a Damsel in Distress who keeps them occupied intentionally or not, or a villain manipulating them into a MacGuffin Delivery Service, so they don't think to question if they're doing the right thing.
    • Example: The Absorbing Man can turn his body into anything he wants, but his low IQ and limited imagination means he rarely does anything more than turn into a hard substance to bash the heroes.
  • Physical: Giving a character an injury can be a great way to not just keep them housebound, but start the plot itself. Other physical limits include ankle bracelets (Disturbia) or the more exotic Power Limiter.
    • Example: In The Dead Zone Johnny has psychometry from a post car-crash coma, but also has a constant limp that requires him to use a cane. Considering how often he has to outrun danger, this is a serious problem for him.

    General External Limitations 
External limitations are those the setting or environment place on the characters and their actions. These can take a wide variety of forms, for example a character could be prevented from shooting an enemy by having a gas leak make it suicidal. Or the setting itself may be designed to keep a character from doing something, either by punishing the action or inhibiting it. For example, a hero who has access to awesome future technology can't use it without breaking the Masquerade, or a villain with the power to kill enemies with voodoo dolls risks attracting the attention of killer flying time monkeys. As this last one shows, you do have to be careful to keep it believable.

Physical Environment:

The geographical area the hero is in can be used to make their choices a lot more limited. The section How to keep a character from leaving already details how to use it to cut them off from escape and help, but the environment can also be used to make things like fighting, thinking, or even talking hard if not impossible. All you have to do is arrange it so that what you don't want them doing is naturally impossible. For example: two of the heroes could normally beat up or catch their enemy, having the hero run into the bad guy in a night club full of strobe lighting, lots of Innocent Bystanders, and impossibly loud music makes it a lot harder for the hero. To that end, consider engineering the story or scene to take place somewhere that is hard to see, hear, or think in (the aforementioned club would be a poor place for any hero in his cups to make an important decision).


Peer pressure, social responsibility and family duty all serve as ways to force a character to do (or not do) something. A sufficiently honor-bound character would follow the lead of the community and its laws, but a rebel can be hemmed in by the Obstructive Bureaucrat, the distrust of All of the Other Reindeer, and fight against a populace that is getting slaughtered. Outside enforcement like police, bosses, criminals or the army can dissuade certain actions as a way of threatening heroes into complying.
  • Example: In Neverwhere, the heroes and the villains run into each other in a marketplace. Normally, they would have fought to the death, but the market truce meant the bad guys had to be civil or face death by mob.

Setting / World:

Beyond making the immediate area force or stop an action, the setting itself can be engineered to keep the characters in line. This can be done by altering the "default" settings from Real Life to make the plot work, characters can be made to act differently than they would in the real world. For example, if the fictional city the characters inhabit doesn't accept recordings from wiretaps as valid evidence, then it justifies their trouble with bringing down a crime boss. This manipulation can be used not just on legal or social laws, but also physical ones. In a setting with Magic and Powers, making it so the Phlebotinum that gives the heroine and Big Bad powers only works in the Dark World, so neither can attack each other in the Muggle world with a decisive edge. With this kind of limitation, remember to be consistent and to state the limitation early enough that it doesn't become an Ass Pull.
  • Example: In ×××HOLiC, Yuko is a very, very powerful mage, but due to a complicated system of Equivalent Exchange, she can't help Watanuki with his problems without massively indebting him to her.


There's a Villain-Beating Artifact that would end the plot in seconds? Destroy it or deny access to it, forcing the heroes to find a different way to win.

Media examples

    Multiple media 

    Anime And Manga 
  • Inuyasha's Miroku has what is basically a miniature black hole in his hand which can suck in and destroy even ridiculously powerful beings. For no reason besides the fact that he's not the main character, he is poisoned if he sucks in venomous insects or toxic gas. It is also established that if he uses this too much, it will eventually swallow him whole. Immediately after he joins the main cast the villain calls up a swarm of giant wasps that protect basically everything that has to do with the main plot.
  • In Re:Zero, Subaru's life would be a lot simpler if he just told people about his Return by Death ability. Problem is, he can't due to the Witch's interference, which almost literally paralyzes him with fear whenever he tries. At one point he even decides he's going to just power through that fear and tell someone anyway, but the Witch retaliates by killing the person he was going to tell. He's not keeping it a secret out of a belief that his friends can't handle the truth, a lack of faith in them, or even a fear that he won't be believed — there is a force that is very deliberately stopping him from telling anyone.
  • Lina Inverse from Slayers can perform the Giga Slave, a spell which is literally capable of destroying ANYTHING, including gods. The reason she doesn't perform it more often? Because destroying anything is just a small subset of what the spell is truly capable of doing, which is destroying everything. This is generally handled fairly well in the story, with the spell and Linas ability to cast it introduced surprisingly early on, and it's use is a central plot element to the first three seasons. In season one, after she performs it, a Copy Rezo wants it cast at him so that he can prove he's stronger than the original. She manages to find an alternative solution, however. In season two, the entire point of the events of the story was to manipulate Lina into casting the spell so that one of the settings strongest demons can bring about The End of the World as We Know It. In season three, it is never actually cast, but a large portion of the season is built around finding another way to defeat the Big Bad that isn't nearly so risky to existence. Even as they are preparing their 'safer' alternative, it's still mentioned that if their plan doesn't show any sign of working, she's ready to cast the spell as a last resort.
    • Another example: Want to ensure your heroes can't use their awesome item/weapon for a time? In one battle, Gourry can't draw his Sword of Light for fear the enemy will learn that he has it, because the enemy's goal (bad news for the world) requires him to find more of these powerful artifacts. And since Gourry's major power in a fight is swinging a sword, that keeps him out of the battle until he uses his sword to protect Lina, thus revealing its presence and having it immediately captured by the enemy.
  • In A Certain Magical Index, Index has a magical robe called the Walking Church that renders her immune to virtually all attacks. One of the first things that happens is Touma destroys it to prove the power of his Anti-Magic right hand.
    • Accelerator is the most powerful Esper in Academy City, bar-none. His powers over vectors make him nigh-untouchable and he can kill people with just a touch. However, his powers require him to do numerous vector calculations. While he's plenty smart enough to do them, one of the first things that happens when he becomes the Deuteragonist is that he gets shot in the head. The resulting brain damage forces him to walk with a cane and prevents him from making the necessary calculations for his powers unless he's connected to the Misaka Network through his battery-powered choker, which only has enough power for 15 minutes a day.
  • Spy X Family:
    • It's a spy story, Anya is a telepath. She can easily read the thoughts of anyone she meets, allowing her to ferret out the many secrets surrounding her. She doesn't even have any Power Incontinence or Sensory Overload problems; she is in complete control of her power. What keeps her from completely breaking the story? She's five. Despite knowing all about her father's secret spy missions, she constantly misinterprets what's actually going on or jumping to conclusions about what the best answer to the problems he's facing would be.
    • Bond might be an even bigger potential story breaker. He can see the future, and while his visions aren't perfectly controlled they are easy to understand and always accurate, and he has Undying Loyalty to Anya. But he's a dog. A non-uplifted dog. The only reason he's useful at all is because Anya can (with effort) read his mind and share his visions.

    Comic Books 
  • Superman: Why else is kryptonite everywhere?
  • Dr. Manhattan: It just so happens that the one almost completely omnipotent character in the story is also almost completely apathetic, so he spends his time looking at elemental particles and doing whatever the government tells him instead of, say, secretly defusing all nuclear weapons in the world to avert the threatening apocalypse that fuels the plot. Also, the only things that are mentioned as actually beyond his powers to do are to stop all Soviet nuclear missiles if they were fired at the USA at once, and to see and reveal the conclusion of the plot clearly.
    • It's also very well-established that while he's got senses no one else has, he's not omniscient and many of his senses aren't particularly any better than anyone else's. So in the aforementioned nuke idea, he'd first have to figure out the location of all of the world's nukes. After that, sneaking up to defuse them all before someone panicked and launched the rest would be possibly MORE difficult for him than others, since he's a blue-glowing giant and can only be in four or so places at once that we see.

    Fan Works 
  • In Yudkowsky's Harry Potter and the Methods of Rationality, there is an excellent example of an external geographic limitation: it is explicitly stated that the direction of time cannot be changed inside Azkaban. This prevents any Fridge Logic concerning why Harry doesn't just use his Time-Turner to get out of a bad situation, as he had already demonstrated a willingness to do on numerous previous occasions.
    • And before that, the Time-Turners themselves. In canon, we were never given any rules about their limits. Here, any individual Time-Turner can only be used six times a day, and no combination of Time-Turners can take anyone or anything back more than six hours. Not to mention that it always turns into a Stable Time Loop.
  • In The Keys Stand Alone, the four are happy to use their overwhelming magic—except, as Actual Pacifists, they're not willing to kill or even harm things, so they self-limit all the time.
  • White Sheep (RWBY): The Grimm are an endless army of Perpetual Motion Monsters who can be controlled by a single individual with Complete Immortality. How does that army keep from solving every problem when the heroes have it? The one in control just wants peace. Actual peace, not "kill everyone who disagrees with me" peace. An unstoppable army that the whole world hates is actively detrimental to that.

  • Eragon cannot use magic to kill his wizard opponents because just before they die, they might kill him too; he has to first control their minds. If he is fighting soldiers they are usually protected by one of the aforementioned wizards.
  • The Dresden Files generally takes pains to have Harry explain why he can't use certain spells or abilities or resources. One of the more common limitations is when Harry is dealing with either humans or monsters who've taken human shields, as the First law of Magic is that you cannot kill a mortal with magic directly. Other Laws of Magic deal with other particularly nasty uses of magic, such as transforming bodies, mental magic, or binding living creatures to one's will. Other times, Harry specifies that while he would ordinarily use a type of magic or call someone for backup or information, but he can't for a particular reason.
    • Also, when Harry displays new abilities, it is carefully justified, neatly avoiding an Ass Pull and a Deus ex Machina.
  • In The First and Second Chronicles of Thomas Covenant the Unbeliever, Covenant possesses the White Gold, a ring with effectively unlimited power in the world of The Land. However, he 1) doesn't know how to activate it throughout most of the first book (it is implied that the key is wild and uncontrolled emotion, which he carefully controls due to his training to deal with his leprosy), and 2) if he uses it at a power level needed to defeat his most powerful enemies, he can destroy the Arch of Time and both end the world and free Lord Foul from his prison.

    Live Action TV 
  • 24, Season 1 uses constant surveillance on Jack Bauer to make sure he doesn't disobey the terrorists' orders (his family is at stake and they will die instantly if he disobeys.)
  • As a series which has a hero who owns and uses a time machine, Doctor Who has come up with several reasons why the Doctor can't just pull the old "go back in time and stop the problem from happening before the adventure even starts" move. Given the nature of the series, some of these reasons can be vague or contradictory, but nevertheless:
    • Several episodes mention a principle called the "Blinovitch Limitation Effect" to explain why characters can't just go back in time repeatedly to fix their own mistakes or stop problems from becoming problems in the first place. It's a bit hazy, but in at least one story it's suggested that when a person goes back in time and meets an earlier version of themselves, it creates an effect that at worst can destroy the universe and at least has significant impacts on the person themselves (in the story in question, the earlier version of the person suffers amnesia-related trauma).
    • It is stated in several multi-Doctor episodes (such as "The Three Doctors" and "Time Crash") that the "First Law of Time" means that the Doctor cannot go back in time and meet a previous version of himself without risking the destruction of the universe, unless it is carefully arranged by the Time Lords.
    • In "Pyramids of Mars", one character brings up the fact that she comes from the future as a reason why the Doctor and she can just leave the current adventure (set in Edwardian England), since they know that things worked out okay. In response, the Doctor briefly transports her to the future — wherein Earth is a blasted wasteland because of the outcome of events following the point where they left. It seems that the future can be affected by what happens in the past if time travellers are involved. Later episodes, especially from the new series, describe this as the characters being "part of events now" as a reason for why they can't just leave when things get dangerous, or go back in time to stop the problem from happening at all.
    • New series episodes often allude to various "fixed points in time" which cannot be changed at all, at least not without disastrous consequences. These "fixed points" tend to correlate to various major events in human history (such as the Second World War) or events that the characters would be tempted to change if possible (such as the death of a parent in "Father's Day").
  • In Firefly, River Tam possesses phenomenal physical combat abilities and Psychic Powers. She has both internal and external reasons to not use these to solve everything, because she is both insane and the majority of her combat abilities are buried beneath her insanity until they are triggered by subliminal messaging.
  • One of the better external limiters is from The Greatest American Hero. Ralph is given a super suit by benevolent aliens who know he will not abuse its powers, which are in the instruction manual which accompanies the suit. Naturally, almost as soon as the aliens leave, he loses the manual. The aliens later give him a second instruction manual...which he also loses quickly.

    Video Games 
  • In Five Nights at Freddy's: Security Breach, Gregory attempts to escape the PizzaPlex, but the front door gets blocked off by a security barrier before he could reach it. But couldn't he just leave through the emergency exit? Surely Fazbear Inc., for as incompetent as they have been, would have one available by law, right? They do, but it can only be opened with a VIP pass.
  • In The Reconstruction, Rulian is stripped of his necromancy powers by Tezkhra accidentally. If not, he probably could have simply resurrected the millions who were killed during the rise of the Lord-God, making the ending much less of a downer and allowing an easy reconstruction.
  • In the BlazBlue series, Noel Vermillion acquires/always had not only the power of the Godslayer to kill nearly any living being, but also the Eye of the Azure to create planet-scale Reality Warping. However, she's also a self-doubting wreck who not only lacks the confidence to use her powers properly but more than once denies she even has them at all.

  • Howard Tayler, the author of Schlock Mercenary said in the Writing Excuses podcast that he faced this problem once Petey gained godlike power. His solution? A Greater-Scope Villain. The heroes struggled to defeat one of these foes, then royally pissed off their entire civilization, so for the rest of the series, Petey is stretched thin holding off a galaxy of them in a cosmic cold war. Petey still finds ways to meddle in mortal affairs: 1. comparatively small space miracles, of a god on a budget, and 2. scheming (usually to hire the main characters).
  • In Sluggy Freelance, Torg could probably solve many of the problems he faces with Chaz, but doing so would require the blood of someone innocent to activate it. Of course, he never thinks to collect a vial or two from anyone in the Do L, or to simply cut himself.
  • Last Res0rt has Jigsaw Forte, who can read minds and transform into a Superpowered Evil Side which can handle most of her problems... except for that pesky "being under constant surveillance on a Reality Show" thing, and if she actually reveals she's a vampire, she'll end up hunted down.
    • Also, she's only just turned into a vampire, so she's still learning how to control most of her powers — right now, she can't turn off her mind reading, which means that if everyone starts thinking at once (or one person's mind starts going a mile a minute), she's susceptible to overload.

    Western Animation 
  • In the first series finale of Kim Possible, So The Drama, Kim gains a battle suit that allows her to literally do anything. It makes another appearance when the series is renewed but it becomes hijacked and becomes a case of Holding Back the Phlebotinum. It makes a couple more appearances, then mega geek Cousin Larry gets a hold of it. Kim probably let him keep it after that.
  • In My Little Pony: Friendship Is Magic, Twilight Sparkle is the personal student of Princess Celestia, the ruler of the realm and essentially a physical goddess. Any trouble Twilight cannot handle on her own could potentially be taken care of simply by contacting her teacher. However, due to her deep-seated fear of disappointing Celestia, she never resorts to this, and instead tries to do everything by herself.
    • Twilight's considerable powers and skills are often kept in check by her strong morals; she's never resorted to killing even mindless parasprites, never uses brute force unless physically threatened, and tries for the diplomatic approach as often as possible. In addition, while her magic is extremely powerful, she often messes up spells she's not fully familiar with, which can make things worse.
      • Except for that one time in "Too Many Pinkies" (S 3 E 3) when she destroyed massive amounts of Pinkie clones, which do have minds of their own.