Gemini Destruction Law
In most media, to kill a Hive Mind or cluster creature you will need to kill every last part. Other times you'll luck out and only need to kill the core (or Hive Queen). Then there's this. Basically, it turns out that the monster needs those parts, so if you kill enough of them it'll die. Contrast From a Single Cell.
Examples:Anime and Manga
- In Neon Genesis Evangelion, Israfel was actually two entities which had to be destroyed at exactly the same time or else they would keep coming back. Similarly, Iruel was a nanovirus that kept growing and adapting until they managed to trick it into an evolutionary path that led to self-destruction.
- Jamie Madrox of X-Factor can be temporarily incapacitated when a foe kills any of his duplicates in proximity to him. That would be within a few miles, rather than, say, across the planet or in another dimension.
- Robot Wars entrant Gemini. If 50% of any competitor's drive was destroyed, the competitor was counted out. This rule was removed later.
- His Dark Materials: In an alternate universe, humans have shape-shifting animals called "Daemons" that are basically the other side of their soul. Because of their metaphysical connection, most human-daemon pairs can't bear being separated for more than a few yards as it causes pain and severe mental and emotional trauma. If either the daemon or human dies, the other dies with it also.
- In the Animorphs prequel book The Ellimist Chronicles, Toomin (the Ellimist back when he was mortal) is captured for years and years by Father, a massive tentacled sea monster which has absorbed the minds of everyone it's every killed. Eventually Toomin learns to fight back and absorb the minds into himself. He states that the last mind he absorbed was Father himself, which turned out to be nothing.
- Dungeons & Dragons 1st Edition supplement "Fiend Folio": The Cifal (Colonial Insect-Formed Artificial Life) was a monster made up of a huge number of insects bound together into a humanoid form. It had 10 hit dice altogether, two of them being the binding energy that kept the insects together. If you did two hit dice of damage to it, the insects broke apart and fled. That is, if you did 20% of its total damage, it was defeated.
- Course, then you've pissed off a whole hive of moderately intelligent bugs, who, being demonic, are probably going to want revenge...
- In Halo, the Flood always have a Hive Mind, but it will attain a form of sapience called a Gravemind if the Flood attains enough biomass. Thus, the Monitors on the Halo rings keep the Flood in their labs isolated from any life-forms it can use as a host. 2401-Penitent Tangent, in the second game, neglected his duties, allowing a Gravemind to form on his ring, while either the humans or the Covenant in the first one released the Flood from a lab they thought was a weapons cache.
- In Tsukihime, Nrvnqsr Chaos can only be killed if all 666 creatures that make up his body are killed at once. If they are killed individually, he can instantly regenerate them. This fact makes him nigh-impossible to kill, even for top-tier fighters like Arcueid. Shiki, however... when he kills something, it stays dead, no matter what. So he's able to kill pieces of Nrvnqsr without them regenerating, which freaks the monster out.
- Lufia II: Rise of the Sinistrals had a dungeon boss that split into two, one form being fire-based and the other ice-based, which had to be defeated simultaneously. When the party first fights it, they fight each body one at a time; it regenerates and laughs in their faces. So they split the party in half and two characters fight each body.
- This is referenced in the webcomic Freefall that Florence's species would need 50 individuals for short-term survival and 500 for long-term. Her creators only made 14 Bowman's Wolves total so far, hence one of her main objectives is to ensure they continue.
- Ben 10: One of Ben's alien forms was Ditto, which had the ability to clone itself without limit. Unfortunately their link means that if one clone is hurt, the other clone feels the same pain. In "Divided We Stand", one Ditto was captured by Mad Scientist Dr. Animo and and powers taken to multiply his mutant army, which all died after one was defeated.
- Later duplicating alien Echo Echo doesn't have this problem. All of the Echo Echos we saw in one fight were wiped out by the enemy (namely a Not Himself Kevin) but Ben survived by keeping one of himself in the trunk of his car.
- If any population of a single species is reduced below a certain limit, that population will die out. Humans need at least 1,700 people to repopulate the earth.