# What flaw keeps the mimics out and keeps the humans in?

A set of small isolated human populations, villages, although geographically close stay separate for one reason and one reason alone. Terrifying beasts that hunt human flesh and terrify children at night. The beasts mimic a human appearance, often previous victims, making them excellent at picking off people one by one or getting close enough to launch a surprise assault.

The question is what flaw does this creature have that stops them infiltrating and destroying these villages, and yet can't be used against the creature when humans try to travel outside the villages?

No magical borders that keep the monsters out although geographical features could be used in a similar fashion.

• I assume the mimics can mimic scars and tattoos, not just DNA traits. Yes?
– SRM
Jan 18 '20 at 14:41
• Would the creatures want to destroy villages from within? What is their motivation? Because a tiger is a dangerous predator but it's usually not seen in cities just because it's not interested in going there. If mimics are actually malicious and not just eating people because they can, then they might have a reason to enter a village. Otherwise why bother. It also matters how intelligent they are - can they make complex plans or are they able to do short term planning - let's hunt this person by mimicking that one.
– VLAZ
Jan 18 '20 at 14:52
• This feels more like a brainstorming question than a world-building question. This is really entirely up to you and how you design your mimics and world.
– John
Jan 18 '20 at 15:57
• They smell like terminators. Use dogs at home, which will alert you to their infiltration. Used offensively, all they do is alert the terminators to your presence. Sorry, I mean "mimics". Jan 19 '20 at 21:36
• You called them beasts, so what level of intelligence do they have? Are they able to speak? If they cant speak then easy test right there, and if they can, then a daily password. Jan 20 '20 at 13:09

The way I saw it is the villages are a large source of food a mimic could enter, and as they've blended in stay happy and fed by picking off someone night by night and reproducing. Possibly replacing their victims with said offspring till the village is empty.

I'm going to tackle this because the premise seemed incomplete. I didn't know what motivation would mimics even leave villages. Now, I can say this will definitely not be a motivation.

Let's assume a mimic does get into the village. OK, they've blended in and they can now freely eat anybody they want, right? Well, no - not really. How many are they going to eat? One person a day? Two? Three? Whatever the number is, it's going to be noticeable. People don't just vanish from a village. OK, maybe every once in a while but just disappearing left and right at a regular basis? The village will figure out something is up within a week. Maybe even a couple of days.

Once the village knows people are disappearing, it's not a hard leap to "it's a mimic". The people aren't around and they should be around. There is no bodies left. So, the villagers start a hunt. Whatever form this hunt takes, it will be extremely unpleasant and the mimic will be found within a short order. Mass hysteria is not something that will just "pass". Nor would people just overlook any minor detail that seems out of place. Didn't Alice use to move with a slight limp just before it rained? Didn't Bob always cook a potato soup on Saturday?

A village is really bad for a source of infinite food. Because when food figures out what's happening, it will bring forks to the table. Pitchforks.

As for replacing the village with its offspring? Unless a mimic can reproduce and the offspring reaches maturity (or enough skills and knowledge to mimic somebody reliably) between meals, then that's a no-go. And I'm going to assume that this is not the case, or the mimics will need to eat a lot more and that means that it's even harder to replace on the fly.

The only plausible way a mimic can live within a human village and remain unseen is if it doesn't eat people from the village. Or doesn't do it often enough. Which severely restricts the eating options. You could maybe get away with a person every month. It's a bit hard but maybe you can also kidnap several at once and eat them over time. So, not a lot of meals there. So, a safer option is to venture outside the village to bring in victims to eat. But what's the benefit here? It's still easy to be found out - you have to smuggle your victims without anybody seeing them. And you still have to hunt. So, it's similar to living in the wilderness but with a lot of extra logistics attached that makes the wilderness easier and safer.

• Interestingly, that answer makes a lot of sense because a version of it applies to why real world carnivores don't dwell in human villages, even if humans would make a good meal. Massed humans with pitchforks aren't an easy meal even for a lion.
– Pere
Jan 19 '20 at 1:14
• @Pere : and this is why many strong carnivores and omnivores perfectly capable of killing humans are actually terrified of humans. If you walk alone in the forest and meet a bear, it will usually run away in panic, despite being much stronger and bigger. It will only attack you if cornered and didn't see a quick way out (or you happen to get between a mother and her cubs). We've been hunting large animals for so many millennia, that the ones which didn't evolve a fear of humans went literally extinct. (and this is why it's a bad idea to feed wild animals, as it will erode that fear)
– vsz
Jan 19 '20 at 13:52
• @vsz I would advise that not ALL animals run away. Polar Bears will kill you and then eat you. Jan 20 '20 at 2:08
• @Nelson : polar bears are the exact exception to prove my point: they haven't been evolving around permanent human settlements for long enough.
– vsz
Jan 20 '20 at 5:27
• This would make an interesting premise for a themed mafia game. Jan 20 '20 at 18:45

# Mimics are two-dimensional creatures posing as three-dimensional

Everybody knows that Mimics aren't actually three-dimensional beings, they simply have the ability to mimic them, if you look from the right angle. If you were to ever be able to see one from slightly to the side, it'd look like an animated cardboard cutout.

This strange creature can easily keep its 'front' centered towards its intended target at all times, turning around and showing different 'angles' of a 3d creature with high enough speeds that simply circling it will not reveal it to be a fake, but when you are looking at the 'back' of a mimicked creature, it's still the creature's real front facing, just showing a different image, like a 360 degrees photo of sorts.

This method works great for approaching a lone wanderer, simply keep your front facing towards them and they'll never find out you are as flat as paper. However, as soon as two people are present at the same time, it becomes obvious right away to one of them that you are a Mimic and paper-thin, you can't face two people at once after all.

Avoiding villages has nothing to do with the villages themselves, it's simply about avoiding confronting more than one person at a time.

• This is unique and creative. I like it. Jan 20 '20 at 13:29
• This...would be horrifying, actually. I've played games with a 3D world but 2D NPCs. It's they use a simple technique where the model either faces you or has their back towards you. It works in the game but seeing this in the real world would be really frighting when you actually comprehend you're looking at. I imagine a 2D mimic will use foliage to partially conceal themselves. That, and moving away from sight will maintain the illusion for a while. They might even use their 2D to shock a victim into standing still while they try to comprehend what is so wrong.
– VLAZ
Jan 20 '20 at 18:37
• +1 but this idea doesn't need 2d mimics. It's enough that mimics have a mimic side and a non-mimic back, even if their arent 2d.
– Pere
Jan 22 '20 at 12:10

How about the uncanny valley effect? mimics can look very much like humans but on close inspection they just feel wrong. It works great for getting close to people but once they are close the wrongness gets noticeable. this will work for surprise attacks but any sort of prolong or close exposure would out the mimics

• the eyes, its always the eyes, (and in this case the teeth) Jan 20 '20 at 0:41
1. Mimics cannot talk (or mimics do it badly), and mimics usually has trouble dealing with more than 2-3 humans on the same time. So, nobody of humans leave the village alone, and its mandatory to have short gossip with everybody they meet around the village, to proof, they are not mimics. If people dissapeared for more than one day, they are considered mimics, if they encountered, and they have to provide a good explanation why they were absent

2. mimics, like majority of beasts, are afraid of smell of burning wood, because it reminds them the fire in jungle. If you have big bonfire burning full day, it is excellent repellent against mimics

3. mimics are bad at swimming, and all villages are placed on small islands.

4. mimics cannot kill instantly - probably, their touch paralyse human, and than they consume adult human in few hours in a way, similar to spiders do - put prey in web cocoon, inject digestive ferments in it. If you see mimic trying to consume human, you have about a hour you can call for aid to beat mimic with sticks and stones and release it's victim.

5. mimics are solitary predators "making them excellent at picking off people one by one or getting close enough to launch a surprise assault", but they have issues against well organised group of people - majority of group works (cut trees, gather herbs, etc...) and few lookouts observe people and count everybody to find, if anybody is missing

6. With ability to shapeshift into human, why mimics cannot disguise into humans corpse and hunt other animals? The ones that can be interested in eating human corpse and are easier to hunt (because they are not so smart) - boars, wolfs, bears, prey birds, etc... Probably, mimics smells like dead people, and its something they cannot conceal. So, mimics hunts humans only if there is no any other reliable food sources. As result, mimics are not so eager to hunt people.

7. Mimics are afraid of sound of big drums (no idea, why :-( ). And villagers plays this drums all day, repelling mimics. Theoretically, you can take big drum in journey from village to village, but its quite complicated - you need big cart, because drum is 2+ meters in diameter

• Although I like the ideas a lot, all except number 3 seem like they could be replicated on a journey, number 1 simply requires what you explained but while travelling so larger groups and check ups. Number two requires the carrying of burning wood although you could say the smell would be weaker or blown away so that might work. Number 4 once again would be overcome with groups, as would Number 5 and as for Number 6, if the mimics aren't interested then going out wouldn't be an issue. Jan 18 '20 at 18:38

The small villages gather every day as a group and decide a password. Anyone who doesn’t know the password the next night is a mimic who ate someone that night. This solution doesn’t work between villages because there is no long range communication to coordinate passwords with travelers en route. And it only works initially because they were able early on to certify that there were no mimics in the village... they can never trust that assumption with any other group ever again.

Children too young to talk or understand the password can NEVER be left alone without an adult to speak for them. A kid left alone even once is assumed to be a mimic. Same for senile or mute adults.

• Assuming Mimics are intelligent this plan has it's flaws: xkcd.com/538 Jan 20 '20 at 11:22

I run a game with a similar 'villages are safe from mimics, but travellers not so much' mechanic and the lore explanation there is that a mimic copy can't replicate scars, tattoos, anything that has happened to a body after it was born that changes its appearance.

As a consequence, villagers eventually learn to tattoo their newborns with a simple mark, basically a 'real human' watermark, and as they grow they'll likely accumulate more markings. In villages you can take the time to confirm a mark, see if it washes away, whatever.

Out in the wilds you can't really ask someone to bare wherever they got marked (assuming it's not somewhere bound to be visible, like the nose) and then rub water on it vigorously, and you wouldn't be sure of what mark to look for anyway if its not someone in the village you've known for years.

Trees

The leaves of one of the local trees contain a volatile oil which is a powerful mimic repellent. Human villages have sprung up around clumps of these trees.

Unfortunately, once harvested, the oil rapidly loses its potency, making a journey of more than a day or two away from home a perilous one.

The mimics are managing the human population sustainably.

The mimics are intelligent. They have to be, to successfully mimic humans. And they are organized, the mimics. They live in a society of their own. They pick off humans from the villages one by one not acting as lone wolves but out of a strategy of sustained successful harvest.

They do not come in and overpower the village and glut themselves because that would be shortsighted. What will they eat next month? They need to keep their depredations down to a level that human reproduction can sustain and that is not easy.

But if the mimics wanted to slaughter an entire village, they could probably do it. And if people come through the forest that is what happens, dogs notwithstanding. It suits the mimics to keep the humans isolated. There are more humans than mimics and humans in large groups are hard to deal with. Also the mimics are aware that the best defense is a good offense – if the humans found the mimic nest that would be bad. There may be other things in the forest that the mimics don’t want humans to find.

Maybe the mimics are really illusionists? They're not actually changing shape - They're changing how their prey perceives them. Kind of like a mind effect. That way, they might avoid villages because it's too difficult for them to trick too many minds at once.

While the mimics love human flesh, they cannot survive barely on it. Their digestion requires them to eat every day a particular plant, which is deadly poisonous and very smelly to humans.

This plant is abundant in forests, but no villager would bring it to their home. And because of the smell, all neighbours would immediately know if they did.

At most, a mimic can sneak in, eat their stomach full and then leave to find the plant - or suffer terrible indigestion until they do.

Deadly (house) dust mite allergies. If an allergic reaction proceeds to anaphylaxis, death is a possible outcome. Dust mites are everywhere humans are, especially densely located in the residences and workplaces of humans. However, dust mites do not live on people, so a mimic's risk of exposure to this allergen is very low and can be reduced essentially to zero if clothing is removed before consumption.

One of the main features of a small tribe is that everybody knows everybody.

First case: A mimic wandering into the village looking like a stranger. Distrust of strangers is common enough in our world, without mimics. In a worlds with mimics strangers would not be welcome.

Second case: They mimic somebody from that village who has been in the forest for some reason.

This is not as easy as it sounds. Sure, you can get the looks right, but actually fooling somebody who actually knows that person is nearly impossible.

The villagers know about this danger and will interrogate anybody coming back from the forest before opening the gates to them. "What is your fathers sisters name?" "He has two, Magda and Mary." "You may pass."

Even within the wall people will be on guard for people who doesn't know what they should know.

Not so easy after all.

## The creature's blood is not red.

Upon entering the village, guards give you a knife (could be chained to the door in walled villages) and order you to prove that you are human by making a small cut on your hand.
This gives them a safe way to let people in and out. While it may be dangerous to work outside the city walls, this makes sure it can't get inside.

### They don't eat their vegetables

They eat tasty humans not, ew, plants?! You could perform a simple check to see if someone is a mimic:

Make them eat a piece of fruit. They throw up? Something's up. It would be instantly obvious when the first round of diner is served and they skip they vegtables.
Especially when it's common to eat your vegetables. Bonus: Healthy citizens!

### Mimics have trouble imitating scars and wounds.

The mimic needs to maintain concentration for each bodily detail they represent and would prefer not to emit bodily fluids to simulate bleeding, so they generally have trouble imitating scars and wounds over a long period of time.

Upon entering the village for the first time, it is standard protocol to show existing scars and receive a small cut on your upper arm. Humans will show the following hard-to-emulate characteristics upon being cut:

• The wound will bleed naturally
• The wound does not heal for several days and will remain in the same place over that entire period.
• All scars will be in the same places and have the same appearance every time a person is seen.

If any of these characteristics seem off, you can conclude the person is probably a mimic. At this point, you slice off a fingertip and observe the bleeding, just to be sure. Once confirmed, you then kill the mimic.

Birthmarks, freckles, and moles would also be part of this process. A few people in the town have the responsibility to document scars, birthmarks, moles, and freckles and act as gatekeepers. For the scabs, it may also be common for them to pick scabs as a test of authenticity.

Travelers that come across each other can give the customary cut, but with only a few minutes of observation, they aren't really able to do a better test and simply maintain a defensive posture of distrust as they watch the other traveler's cut bleed.

The presence of creatures that mimic and prey on humans like that would be a really big impetus for humans to not live in small, isolated villages and group together in larger settlements. Living in small, isolated villages is about the worst thing you can do to defend against an intelligent predator that pretends to be a human. More people around means its easier for a mimic to get spotted if it slips up, and the mimics don't have an easy alibi of coming from another small village. Small isolated villages would be easy for a mimic to tear apart in a few feedings, especially if these villages are less than forty people or so. Especially because a small settlement is liable to be about half children and elderly. A village like that could easily disappear and if human communities are that small and isolated no one would notice until months later.

A small village is also going to be less separated from the wilderness and have less options for mimic-repellent. Lets say...burning fires repel mimics. A small village might have a handful of fires going at any moment, a small city would have hundreds. Or silver knives kill mimics. A small village has one, and if you lose it you're dead. A small city has many spares. A small village has a larger perimeter-to-area ratio that makes it harder to defend relative to its population size. So the question isn't "what keeps the mimics out" but "why do humans live in such a vulnerable state in the first place". One possibility might be food, there isn't enough food or water for humans to reliably live in large settlements.

Indeed, the best place for a mimic to hide would be within one of the human villages to avoid suspicion, and then going and preying on people from other villages to avoid producing an alarm. Maybe having a job as something like a woodcutter where they can justify going off alone, even better if they can do it in pairs and each mimic can vouch for the other. Travellers coming to the village would also be prime targets, as they could disappear and no one would notice. Indeed, if you can get multiple mimics pretending to be a group that means the whole "if you're alone, you aren't a mimic" means nothing, because a small group could have all been eaten and replaced at once.

There are a bunch of monsters from folklore who do this exact thing. One common story in these cultures is of a person doing something as simple as walking out of a room for five minutes or going to the bathroom and getting killed and replaced. It's amazing to think just how little we are directly aware of people around us.

The question also exists of whether the human communities don't end up mobbing each other The Monsters Are Due On Maple Street-style due to thinking another village could be unintentionally harboring mimics or even outright replaced by mimics. People in those kinds of situations, where they're surrounded by a predator they have to worry about every minute of every day but can't do anything practical about it, tend to be very paranoid and short-fused and liable to make stupid, extreme decisions in the belief that they're fixing the problem.

Indeed, if the mimics are all hiding in the forest and the people can't do much about them, they may be pushed to such extremes that they decide to burn the forest down and to heck with the consequences, hoping to survive on what food they have stored up until they can plant again.

Mimics crash, when they try or prepare to mimic other mimics.. Its just that two systems adapting to on another can get locked in a loop of eternal refinement. So there can only be one else there would be only none.

The beasts mimic a human appearance, often previous victims, making them excellent at picking off people one by one or getting close enough to launch a surprise assault.

This. Mimics can only mimic previous victims. Therefore they cannot mimic anybody that's alive. Since the isolated villages are small, everyone remembers everyone else from their village who is alive. And, put simply, they don't trust any other human that's not one of their known living members.

This both explains why villages are isolated from each other, and why the mimic's flaw can't be used against them when a person goes outside the village. Basically you are only safe if you live in a community where you have the faces of all your community members memorized. As an added detail, this is also a good reason for each community to make it illegal to leave the community, with the punishment being permanent exile. Because if your community member leaves, and then comes back later, you don't know if it's the same person coming back.

• Fred goes to the woods. Fred is killed by a mimc. Fred is now a previous victim. "Fred" walks into the village. Hi, Fred!
– VLAZ
Jan 20 '20 at 18:28

Terminators were mentioned in the comments and I think that's a key to a good answer. The advanced terminators can mimic human appearance but they're made of metal--they're a lot heavier than what they are copying.

Thus all entrances to the village have simple scales--a guard watches you walk across an object with a counterweight. You cross at the point consistent with your apparent weight. Human, it stays up. Mimic, too heavy, it tips. Look small but cross where a big person should, the guard stops you.

Mimics prey on humans, and they can distinguish between a human and another mimic by some detail only they notice.

But while one stray human is a delicacy, too many in one place are sensorial overload. The mimic will go crazy by picking up the scent, sight or sound of too many humans and lose their ability to shapeshift. Just like a shark smelling blood, they will attack without much regard for their own safety.

This might happen every once in a while by accident, which is a nice reminder to antissocial people that the loner trait will eventually be wiped from the gene pool.

Tails. Let's assume the mimics are wolf spirits, and they like human flesh. However, they cannot transform their tails, so one look at the mimic's backside, and wham, they smack the mimic away.

It could be simply that mimicry only goes so far. I disagree with those who claim that mimics would have differently colored blood, smell like corpses, be unusually heavy, etc. See, these things have evolved to mimic people. That means they have evolved to infiltrate human society, and considering the complexity of a leaf insect or octopus' camouflage, it's quite likely these things can perfectly mimic the human body, at least on the outside.

However, it's what on the inside that counts, or in other words, the mind and heart. Let's say the mimic takes out and takes the place of an artisan. There are two big problems with this the mimic can't overcome: A) it lacks the artisan's creative vision and B) it lacks his/her passion. It also doesn't know the thousand little things that go into everyday social interaction: inside jokes, what relationships the victim has, how he/she behaves around different people (because we do, generally, become different people depending on who we're with).....the list goes on and on.

If you want your mimics to be a viable threat, you need to give them the four following traits:

1. Intelligence (must be cunning to evade and/or negate suspicion)
2. Intuitive (must be perceptive, have highly honed social instincts-in other words, it needs the sociopath's abilities to understand other people despite having messed-up instincts)
3. (may neutralize 2, but unlikely) Power of Inheritance: Once a mimic ingests a victim, their magic-infused digestive system converts the victim's DNA into a form the mimic can absorb and turn into another form. However, there are drawbacks to this:

a. Genetic Memory-While this enables the Mimic to know all the important details that allow them to pull off this trickery, it also gives them the meaning that goes with those memories. A normal Mimic may not access this meaning, as it's brain does not have the right structure to process it, but a Mimic with a recessive gene will. In other words, it will carry all the sentiments that artisan collected over his lifetime. b. Genetics has Little to Do With Personality-One of the arguments against cloning pets is that personality isn't determined purely by genetics. You may have an angelic bulldog for a pet, but his clone may be temperamental and just plain mean. In other words, the Mimic will most likely still lack the creative style or idiosyncrasies of their victim, a potentially fatal flaw.

For evidence of the above statement on genetics, please check out this link: https://www.fda.gov/animal-veterinary/animal-cloning/myths-about-cloning#:~:text=to%20the%20top-,Myth%3A%20Clones%20have%20exactly%20the%20same%20temperament%20and%20personality%20as,%E2%80%9Cnature%20versus%20nurture%E2%80%9D%20argument.If it doesn't work, please let me know so I can fix it.

Finally, an alternative method is that the Mimic somehow 'absorbs' their victim, integrating their very being into their own. This of course comes with problems of its own-what if the victim manages to retain some control, or takes back their new body? If the Mimic is killed, would the victim's spirit take over the body and simply resume life as best they can?

This may result in a Gothic/medieval version of Among Us, where the 'crewmates' (AKA villagers) would be trying to root out and destroy the shapeshifting aliens (AKA monsters, Mimics).