-->'''Narrator:''' I felt like putting a bullet between the eyes of every panda that wouldn't screw to save its species.
-->-- ''FightClub''

Thanks to AppliedPhlebotinum, two characters are in a situation where they have to have sex in order to save their lives. Frequently used in FanFic, especially SlashFic. Seems to Originate in Star Trek TOS with the Vulcans having a seven year itch that requires them to mate, die or KILL!

A variety of DeusSexMachina. Compare with AliensMadeThemDoIt.
----
!!Examples:

[[foldercontrol]]

[[folder:Anime and Manga]]
* In a yaoi called Animal X a race of reptile like people need to breed to save their race, the only problem is there are zero females and they dont want to mix blood with humans, so when one of them does find a guy [[spoiler: who turns out was a girl at birth( even though no one told him)]] and he has their blood, well the whole thing turns into this guy who didnt even know he was a girl being nearly raped(eaten in one occasion where the guy was hungry and forgot he what he was suppose to do) by every other guy he encounters, plus [[spoiler: he is slowly turning back into a girl.]]
* ''YuGiOhTheAbridgedSeries'', episode 16:
--> '''Tristan''': He wants a virgin sacrifice! Quick, Téa, have sex with me! It's the only way to stop him!
--> '''Téa''': Hell no, I'm saving myself for Yuugi! ...I mean marriage.
* ''NinjaScroll'' gives us Jubei, poisoned and seeking the antidote. As it turns out, the only way to stop the poison is with more poison. Good thing his partner is a sexy ninja with a KissOfDeath.
[[/folder]]

[[folder:Comic Books]]
* ''ElfQuest'' has Recognition, a telepathic mating urge that forces elf couples with good genetic matches to mate and have children. Elves who try to resist become sick.
[[/folder]]

[[folder:Fan Fic]]
* In the ''HarryPotter'' fandom, the Snape/Lupin [[{{Shipping}} ship]] saw a great number of {{fanfic}}s using this trope, where Snape and Lupin were imprisoned together right before a full moon. This would mean Snape's death as soon as Lupin took upon his werewolf form, but if Lupin considered Snape as his "mate", the werewolf would spare them. Therefore...
** A particularly horrible fanfic featured a once-in-1000-years event where Hogwarts ghosts would compulsively kill anyone who was innocent (i.e. a virgin). Hermione didn't quite get out, so ''Snape'' had to go in to rescue her... yes, ''that'' way.
** It was also a particular favorite of Harry/Draco writers, who invented the Male Veela fic, where poor Draco had to bond (sexually, of course) with his Soul Mate, or perish. Naturally, his worst enemy was his destined Soul Mate.
** The fandom has an [[EpilepticTrees Epileptic Forest]] involving the sex lives of werewolves, with (mostly SlashFic) writers coming up with new ways of [[HandWave justifying]] Lupin shagging anyone in the cast.
* A ''ChronoCrusade'' fanfic used this trope explaining that Chrono needed to give some of his legion to turn Rosette into a demon so she could feed him astral energy [[DeusSexMachina and apparently digestion would dissolve the legion and blood transfusion would kill her.]] In this trouper's opinion, it's executed a lot better than it sounds.
* In ''StarTrek'' fandom, Vulcans go through something similar called "Pon Farr." The very ''origin'' of {{Slash Fic}}s comes from corny situations where Spock had to mate with someone (Kirk) "or else." The various shows themselves found loopholes to get out of the implications.
** It was 'Mate or Die' originally, but turned into 'Mate, Fight or Die' to give the writers an out in the ST: Voyager episode 'Blood Fever'. The idea in TOS 'Amok Time' was that if anyone challenged a Vulcan's right to his wife while he was in the throes of the blood fever they'd literally have to kill him to stop him. Later writers missed the point (perhaps intentionally) [[spoiler:that Spock was snapped out of Pon Farr by the shock of thinking he'd killed his friend. His line "It must have been the combat" was a cover for this (embarrassing) emotional reaction.]]
* Frequently done in ''TheLordOfTheRings'' fanfic, often though not always with Elves. [[http://tinni.s43.eatj.com/index.jsp This site]] debunks the idea.
-->"This is a fanon invention that has Elves, who are dying either of wounds or grief, "bond" with another Elf or man, by mingling their blood, having sex and thus getting new strength; sort of leeching life off the other and forever living like that. In this case, if one of the Elves "bonded" dies then the remaining Elf must find someone else to bond with or also die. I found no explicit or implicit grounds for this in Tolkien's writing. Still a very interesting concept. Once again Laws and Customs of the Eldar, History of Middle-earth: Morgoth's Ring holds the most information regarding elven relationships."
[[/folder]]

[[folder:Film]]
* In the (very early) Jim Carrey comedy ''Once Bitten'', the ancient vampire played by Lauren Hutton has to feed on the blood of teenage male virgins to renew her youth. Carrey's girlfriend saves him before the third (final) bite. No, not by killing the vampire, smart guy.
** ''Andy Warhol's Dracula'' has a similar situation, though the hero doesn't really care if the heroine gives consent.
* Film example, Stephen Chow movie ''Royal Tramp'' 2. A villainness is hit with a poison that will kill her before dawn unless she mates with a man. The lucky man turns out to be, you guessed it, Stephen Chow.
[[/folder]]

[[folder:Literature]]
* The book ''The Mote In God's Eye'' by Larry Niven and Jerry Pournelle invokes this without the AppliedPhlebotinum. The plot of the novel involves FirstContact with a species of aliens who literally die if they don't mate and get pregnant due to their BizarreAlienBiology. The resulting overpopulation hasn't been very good for their long-term prospects as a civilization.
* In the novel ''Innocence'' by Jane Mendelsohn, the main character believes that her stepmother will kill her to drink her virgin menstrual blood. She conveniently has a boyfriend, so she cures herself of this virginity thing, [[spoiler:much to the anger of the stepmother, who really ''was'' after her blood. Then again, considering the MindScrew plot, it's kind of a OrWasIt at the end.]]
* A rather bad romance novel called ''Heart's Surrender'' featured a race of [[PettingZooPeople vaguely feline]] HumanAliens...who were at very least ''unlikely'' to survive the night if they didn't have sex when their planet's three moons were aligned.
* Used in the ''{{Dragonlance}}'' short story ''Raistlin's Daughter'', in which a mysterious woman accidentally forms a painful magical connection with the titular character that can only be severed if she bears his child. When she finally tracks him down and gets him alone so she can explain, Raistlin is [[{{Understatement}} less than pleased]]. Of course, they're conveniently alone in a cave in the middle of a blizzard with no reliable source of heat, SoYeah.
* Played straight in Sherman Alexie's short story "The Sin Eaters", where the narrator is [[ShotaCon twelve years old]] and all the Indians are [[PuttingOnTheReich rounded up and placed in facilities]] where they are forced to donate blood and amrrow. This is because Indians have an immune gene of some kind that protects against a virus, or something. They talk about antibodies, and that's all I know. Anyway, the government forces him to breed with a thirty-year-old woman who has already been with several men because [[YouFailBiologyForever the more men she's with, the stronger the child will be]]. That last one, despite failing biology forever, oddly fits with native mythology.
* ''The Jennifer Morgue'' by Charles Stross has Ramona Random, an assassin from the CIA's occult equivalent with a succubus bound to her soul. The thing is regularly "fed" by consuming the souls of people Ramona has sex with... and when it gets hungry and Ramona's mark dies of a heart attack before climaxing, she's in a rough spot, as "if it doesn't get the little death, it'll go straight for the big one."
[[/folder]]

[[folder:Live Action TV]]
* One of the most common examples is, of course, the "we're trapped somewhere really cold" situation, where [[IntimateHealing there's only one logical way to get warm]] . . . This is partially TruthInTelevision, because the most effective way to warm up a hypothermia patient in the wilderness is to share a sleeping bag with them, but both the warmer and warmee can keep their underwear on.
** One example of this was an episode of ''{{Taxi}}'', with Latka Gravis and some random female cabdriver. They do it, and it almost destroys Latka's marriage.
** Played for laughs in ''BoyMeetsWorld'' when Eric and a rather attractive female co-worker with a good deal of out door survival knowledge get trapped in their car. She does this once Eric begins to sucumb to the cold (off screen of course, as this is Disney) and explains how they survived later. Eric is mortified that she didn't wake him so he could enjoy being under the cover of a sleeping bag naked with a girl. She does seriously point out that they were in a little more danger than casual sex would permit.
* This is -- no, really-- canon in ''{{Skins}}'', with bonus incest: in retaliation for a vicious prank, Josh Stock kidnapps Tony's sister Effy, overdoses her with heroin, and tries to force Tony to have sex with her before he'll call an ambulance, although he inexplicably (very likely for real-life reasons having to do with Kaya Scodelario's age) backs down rather than make them go through with it.
* The writers of ''RedDwarf'' wrote a script "Identity Within", where the Cat has to breed with a female of his species or be killed by a growing poison sac in his body (a reading of the script by Chris Barrie is available on the Series VII DVD). Unfortunately it proved too expensive to film, which means (ironically) that Red Dwarf's resident ladies man is the only member of the crew who never gets laid.
* In ''StarTrekTheOriginalSeries'' in the episode "Amok Time" Spock must return to Vulcan and mate or he will die. Apparently all Vulcans go through this process (known as Pon Farr) every 7 years. The situation is subverted when Spock believes he has killed Kirk and finds he's no longer in the mood. (this episode probably launched more SlashFic than this troper can even imagine).
** Try just "[[TropeMaker launched]] SlashFic in general". Hmm, Spock suddenly didn't need teh sexxorz after he thought he'd killed his [[HeterosexualLifePartners best]] [[HoYay friend]]? Gee, I wonder what the implications of that are?
[[/folder]]

[[folder:Oral Tradition]]
* This trope is the basis for an old joke: A doctor and his residents are making the rounds when they discover a man masturbating in one of the examination rooms. One of the residents asks why he is doing this, and the Doctor explains: "This man has a rare condition where he must have an orgasm every hour or it will cause a fatal hemorrhage." Several rooms later, they come across a man receiving a blowjob from a [[HelloNurse gorgeous blonde nurse]]. Again the residents ask what's happening and the doctor responds: "Same problem, better insurance."
** Heh heh, "[[IncrediblyLamePun Oral Tradition]]"...
[[/folder]]

[[folder:Real Life]]
* One Real Life example is the unfortunate female ferret - who, if she goes into heat and doesn't get bred, will soon die of aplastic anaemia as her bone marrow stops producing red blood cells.
* This is a myth. I kept three female ferrets as pets when I was a teenager, and they went into heat & unmated several times without any ill-effects.
** In a pinch, however, she can masturbate with a pebble.
** And this is yet another reason most states only allow ferrets to be sold as pets after they are neutered.
** Imagine the implications for [[AddedAlliterativeAppeal female furry ferrets]]...
** In comparison, female housecats' ovaries will crystallize if the cat goes too long without a first litter, with life-shortening implications. Of course, spaying eliminates the problem entirely.
*** And I believe guinea pigs need to have a first litter before the age of six months, otherwise their pelvic bones fuse together and make delivery much more difficult.
*** Of course, humans statistically live longer when sexually active.
[[/folder]]

[[folder:Video Games]]
* ''{{Tsukihime}}'' plays this literally; [[spoiler: making sexy time is the only way to hold back [[EnemyWithin Roa]] in Ciel's route. She likes it in the ass, though, so it may not exactly be mating.]]
** And then there are Hisui and Kohaku's routes, [[spoiler:as the two girls are "Synchronizers" and can boost the energy and healing of anyone they have sex with. Hisui's [[TheirFirstTime first time]] with Shiki, [[MemeticMutation Lord of Bedroom Jackassery]], is used to save him from energy drain and Kohaku's poisons. Kohaku does it to recharge Shiki in her route, as well, and Makihisa's rationale for raping her when she was a little girl was that if he didn't use her power, he'd go insane]].
* In the visual novel of ''FateStayNight'' people can share their magical energy by having sex. This paves the way for [[spoiler: Shirou and Saber having sex before confronting Berserker and Archer on two separate occasions, and Shirou having sex with Rin before fighting Archer in the UBW section of the novel.]]
** This also holds for HF, due to [[spoiler:the fact that the worms in Sakura's body and the strain of maintaining Rider are burning up her prana like crazy, which makes her clamor for anything that can restore it. Largely meaning sex. It starts out embarrassing for her and Shirou, but [[ThePowerOfLove they're in love, so they don't mind]]]]. Rather [[{{Squick}} squickily]], this is also the reason why [[spoiler:Zouken had [[BrotherSisterIncest Shinji]] [[RapeAsBackstory regularly rape Sakura]] and was implied to have done so himself--training her with Crest Worms massacred her prana supply]].
[[/folder]]

[[folder:Webcomics]]
* In a rather... controversial flashback of ''Dominic Deegan: Oracle for Hire'', Stonewater rescues young (underage) Melna from execution by claiming her as his wife. Melna's tribe holds to the tradition that claiming a wife requires physical consummation. Also, [[RapeIsLove Melna is emotionally hysterical and unable to give effective consent...]]
** It should perhaps be stated that the "...Or Die" part of the trope comes in as the orc tribe who ruled in that area was in the habit of slaughtering orphaned girls just because they didn't want to be responsible for said orphans. (we won't mention how she came to be an orphan in the first place) Either Stonewater raped Melna, thus claiming her as his wife and his responsibility, or she'd be cut down by about a dozen archers, or possibly worse. And in Stonewater's defense, despite the alternative he was quite sickened by the act and hadn't known what he was getting into when he claimed her, plus he was about the same age himself.
***So the character has a "defense", but what about the author?
****Well, in Mookie's defense, the incident was portrayed very sympathetically, as a source of trauma for both Melna and Stonewater. It was ''supposed'' to be a horrible situation, but it was written so off-handedly that it came out horrible in a way that Mookie didn't intend, leading to the InternetBackdraft that followed.
**Furthermore, years after the initial revelation, [[http://www.dominic-deegan.com/view.php?date=2009-09-28 Melna returns to her home tribe and confronts the chief that forced the situation]] . She calls him out about how he was the one responsible for her parents' murder and effectively raping both her and Stonewater. No one in the tribe stood up for the chief's decision, and when he attacks her, she knocks his head off.

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