Loyal Phlebotinum

It is a truth universally acknowledged that weapons are just as capable of choosing owners as people are of choosing weapons. If you're an aspiring Evil Overlord trying to Take Over the World, what's the one thing more frustrating than needing a Clingy MacGuffin that you just cannot steal from The Hero? Needing a weapon or magical artifact that you can steal, but it still won't do you any good. For some Empathic Weapons, Possession most definitely does not imply Mastery. Loyal Phlebotinum refuses to work for anyone but its Chosen One, no matter who else steals, wins, or accidentally comes across it. The owner does not even necessarily have to approve of this choice, but Synchronization usually prevents that, making you inexplicably feel like this sword is the one you're meant to have, or that this dragon is just a better partner for you than any others.

Some phlebotinum may be loyal to only one specific person, for reasons ranging from ancestry to destiny. Or it may just be loyal only to someone worthy enough, which usually involves virginity or purity of heart or the like. Names, voices, sentience, and/or a Psychic Link that allows the owner to find it when lost are possible but not universal traits.

Variations include:
 * Mons, Cool Pets, Ridiculously Human Robots, and other Attack Animals who only allow a master worthy of owning such a creature to tame them.
 * Articles of clothing that can only be worn by someone who fits some sort of criteria.
 * Literal and inverted Weapons of Choice.

Be forewarned that such devices can actively discourage unauthorized people from using them—typically in the form of a painful zap. If a desperate villain is willing to risk this, the only options are:


 * Destroy it so at least that meddlesome hero no longer has its advantage (he's probably nothing without his phlebotinum, anyway).
 * Blackmail The Hero into using it for you (hold the Love Interest at gunpoint, dangle helpless children over a Shark Pool, etc.).
 * Hope that its loyalty will shift under the rules of You Kill It, You Bought It (no guarantee).
 * Trying to find out how much of the authorized user is really needed as a key.

Sub-Trope of Situational Sword.

Anime and Manga

 * In the Tenchi Muyo! OAVs, the Master Key/Tenchi-ken is like this, as it can only be used by Juraians of royal blood. This is why Ryoko couldn't take her gems back and why Ayeka used the key as a torture device.
 * The Vision of Escaflowne: The guymelef Escaflowne will only work for Van Fannel, because his blood was mixed with its egergist crystal.
 * Samehada, Kisame's sword in Naruto.
 * The Kaleidosticks in Fate Kaleid Liner Prisma Illya: Much to the annoyance of Rin and Luvia, their Kaledosticks decided that they wanted new owners... while the both of them were using the wands to fly in mid-air.
 * The Digivices, crests, Digi-eggs, etc. of the various Digimon series (not to mention the Digimon themselves).
 * Inuyasha: Several of weapons fit this trope.
 * Tessaiga initially appears to be this, requiring compassion and half-human, half-youkai heritage to use so only Inu-yasha can wield it. Then it seems to be subverted when Sesshoumaru reveals he can use it more easily than Inu-Yasha can—it's simply the youkai-repelling barrier that prevents him from doing so. This fact is what keeps the true ownership of the sword from being properly decided between the two brothers for a long time until eventually Tessaiga gives Sesshoumaru the proof he seeks in a Die or Fly test of Inu-Yasha's worth—every time Sesshoumaru steals Tessaiga's power, the power immediately returns to Inu-Yasha.
 * A more straight-forward example is Toukijin who is so powerful and evil not even Toutousai can approach it. Sesshoumaru overcomes the blade's evil will easily and the sword obeys him loyally from that point.
 * Tenseiga is also this. It accepts only Sesshoumaru as its true master even though Sesshoumaru doesn't want it at all.
 * The Escudo weapons in Magic Knight Rayearth, to the point that Hikaru, Umi, and Fuu can't even use each others' weapons. Hikaru's sword burns anyone besides Hikaru who tries to wield it, Umi's sword turns into water and cannot be picked up by anyone except Umi, and Fuu's sword becomes ridiculously heavy when anyone but her tries to use it.
 * Royal Treasure-type artifacts in The Twelve Kingdoms answer only to their proper ruler. The sword that Nakajima receives near the beginning is one of these—in her hands, it can slay Yokai, while another cannot even draw it from its sheath. (Later, she is forced to destroy the sheath, so anyone can draw it—but it's still just an ordinary sword in their hands.) This property ends up being quite important, since her possession of and ability with the sword proves her royal status.
 * Neon Genesis Evangelion: After the dummy plug incident, Unit-01 won't work for anyone but Shinji. The Evangelions generally don't work very well for anyone other than their designated pilot. NERV does experiment with switching pilots into different Evas, but it doesn't accomplish much except making Unit-00 go berserk (again) when Shinji is placed in it.
 * Raising Heart in the Lyrical Nanoha franchise - everybody else needs to recite a long passcode in order to use her at all, but she'll go out of her way to make Nanoha happy.

Comic Books
""If he be worthy...""
 * Green Lantern
 * When Green Lantern Abin Sur is dying, he commands his power ring to find and fetch a suitable replacement. It brings test pilot Hal Jordan, who takes up the ring.
 * The comics have been highly inconsistent with regard to who can wield a ring. In some stories, only a person who is courageous and has great integrity can use a ring. According to Lex Luthor, "The damn thing's fueled by honesty." However, other stories have entire plots built around a villainous or otherwise unworthy person coming into possession of a ring, usually thanks to forgetting about this power. Though it should be noted that it actually is fueled by willpower, which is neutral in the emotive spectrum.
 * When Kyle Rayner was the only Green Lantern, the ring only worked for him, as former Green Lanterns quickly discovered. Later, he managed to amp up its abilities, so he could control it even if someone else was wearing it.
 * The original Green Lantern's (Alan Scott's) ring put a really nasty spin on this: if worn by someone with malevolent intent, it would kill them.
 * The weapons used by Judge Dredd and his colleagues are equipped with biometric scanners, and each can only be used by its registered owner.
 * In THUNDER Agents, the belt that gives Dynamo his powers has to be carefully calibrated to him; if anybody else uses it, the effect will be misaligned and they'll be torn apart.
 * Marvel Universe: Thor's hammer can generally only be wielded by Thor. Anyone else trying to pick it up will find it impossibly heavy—even The Incredible Hulk! Or even Superman. However, it's not completely exclusive, and on at least one occasion, a worthy and properly-motivated hero has managed to pick it up and use it. This is (as one of the few things about him) fairly accurate to the myth.

Fan Works

 * With Strings Attached
 * George's ring. He doesn't find this out until it's forcibly removed from him, which is like having his soul's arm ripped off. Later he realizes that he's bonded with the ring and it won't work for anyone else. It's probably not an Empathic Weapon, though it can hop of its own volition onto his finger from about a foot away. He can also sense it from far away.
 * John's Kansael as well. This one's definitely an Empathic Weapon. It likes him. No... it loves him. And it's impossible to remove without great care, or would've simply cut it out of his chest in Ehndris.

Films -- Live-Action
""How do I know which Ikran is mine?" "It's the one that'll try to kill you.""
 * Avatar:


 * District 9: Until Wikus was infected by a mysterious black fluid turning him into an alien prawn-hybrid, the MNU was anxious to find a way to somehow operate the alien weapons and machinery, which only functioned with those with prawn DNA.
 * In Blade, the hero's sword handle is booby-trapped so that it will shoot silver spikes into the hand of anyone who doesn't know how to disarm it when they grasp it.
 * In Shoot Em Up, the villains have some pistols with fingerprint locking technology.

Gamebooks

 * In the Lone Wolf gamebook series, the Sommerswerd can only be used to its full potential by a Kai Lord, like the eponymous hero. If wielded in combat by anyone else, it is said that its power will fade and be lost forever. Furthermore, if a truly evil creature makes the mistake of holding the sword—as an ugly dwarf servant of Lord Zahda painfully discovers in Castle Death—it will cost him a few fingers.

Literature

 * Magic Wands in the Harry Potter universe. According to wand-maker Ollivander, "The wand chooses the wizard... And, of course, you will never get such good results with another wizard's wand." You Kill It, You Bought It applies for the Elder Wand,
 * Mendanbar's sword in Patricia Wrede's Enchanted Forest Chronicles: It will only allow itself to be held by the King of the Enchanted Forest or a member of his family. It is innately linked to the forest's magic and in choosing its next bearer when the old one dies, it also selects the next king (who, due to that link, promptly inherits an enormous amount of magical power on top of the title—wouldn't do to have a spell-less leader of an innately magical country, after all).
 * In the Dragonriders of Pern series, each dragon hatchling chooses its future rider.
 * Merry Gentry: Magical items of Faerie—that have been lost for centuries—keep appearing around Merry, and ones that supposedly lost their magic are coming to life in her hands.
 * Wizard's staffs in the Discworld, most notably in Equal Rites, and Sourcery (where the Sourcerer's staff bites another wizard who touches it).
 * Dragons in the Temeraire series can choose at birth to bond with a specific person. In the British Aerial Corps (and presumably in most other countries), the human military leaders try to influence the selection by choosing beforehand who gets to be present at the hatching, but sometimes the dragon refuses to choose anyone (and is therefore sent to the breeding grounds rather than into combat), or chooses someone other than the proffered candidate (as with Laurence and Temeraire, though that was a special case; the egg had been captured in a naval battle and hatched in transit). There is even a specific breed of dragon that will only bond with women. Since dragons live much longer than humans, most of them will have multiple human partners, usually preferring the children of their first partner.
 * The Orb of Aldur from The Belgariad, loyal towards the god Aldur and the descendants of Riva Iron-Grip. And, apparently, the innocent Errand. It was once used by a (different, mad) god to crack the world, and it's NOT interested in being misused again, so hands off unless you're one of the few beings it trusts.
 * The sword Need from the Heralds of Valdemar series is a powerful Empathic Weapon that binds itself to specific women who are about to set off on a life of danger and adventure. It passes itself from bearer to bearer by glowing brightly when handed to its intended recipient. Later it's revealed that Need is more than merely empathic;.
 * In Cryoburn, Armsmen Roic's stunner has the owner-only feature that is being worked on in real life (see below). In earlier works in the series, all stunners are generic.
 * In the Lensman series, the Arisians choose suitable Lensmen, and make a Lens especially for each one. If anyone else tries to wear the Lens, it causes excruciating pain, and quickly kills him.
 * In the Tortall Universe, there's the Dominion Jewel, which can only be wielded by a true ruler. In this case, King Jonathan.
 * The Queen's Thief has Hamiathes's Gift, which will not work for the person who has stolen it; it has to be freely given.

Live-Action TV

 * Doctor Who: The TARDIS is alive and has a psychic link with the Doctor, so don't think she's going to leave her Time Lord without a fight.
 * As different Power Rangers series work differently, the requirements for making the suits work is also different. The series that most have it as a plot point are:
 * Power Rangers Time Force—they link to the DNA of the user, and they only work once the red one has been activated. They had to find an ancestor of their deceased leader before they could power up. Figuring out how to shot web was harder for them than for most any other team. But that's what you get when you steal the morphers and go on an unauthorized mission.
 * Power Rangers Lost Galaxy—the Quasar Sabers could only be wielded by the worthy, and went nuts when a Monster of the Week tried to use them.
 * In Power Rangers Dino Thunder, Dino Gems also choose their users, and non-suited powers can be used even if the gem has been taken. However, no suits without the morpher (which is powered by the gem).
 * The super suit in The Greatest American Hero will only work for the person chosen by its alien creators.
 * The Stargate Verse includes two notable examples:
 * In Stargate SG-1, several pieces of Goa'uld technology will only work for someone with naqadah in the bloodstream—namely Goa'ulds, Tok'ra or former hosts. This include the weapon hand-device, the healing hand-device, and quite likely the personal shields and invisibility cloaks too, as they are never seen used by Jaffa. This aims essentially at enforcing the belief in the mystical powers of the Goa'uld, as they pass off those effects as divine magic.
 * Likewise, many artefacts of the Ancients need to be touched by an Ancient or a human carrier of the "Ancient gene" (probably human descendants of the Ancients that fled from Atlantis) before working. Sometimes, this activation is all that is needed, and the item can then be used by anyone. The Atlantis expedition specifically hired as many gene carriers as they could find, and later managed to circumvent this limitation by inducing the Ancient gene through genic therapy (with variable success, depending on the individual).

Myths & Religion

 * In Norse Mythology, the hammer of Thor would not be wielded by anyone else. It could still be stolen (and is, on at least one occasion), but it's only in the hands of Thor that it turns into a godlike weapon. At least in some versions, that was due to Thor being the only individual strong enough to actually throw the hammer rather than any loyalty on its part.
 * Bucephalus was said to only let Alexander the Great ride him. There's a a story where Alexander is pretty much solely responsible for the creation of Bucephalus, and trained him so that he would only allow him to ride it. (And attached a golden horn to its forehead, just because he wanted a magical sort of horse.) Indeed, no-one could even approach the animal, let alone ride it—until one fateful day, when King Philip lets his three-year-old son, also named Alexander (different son from a different wife) to mount the horse. Alexander finds his half-brother riding his horse, and can barely hold in his rage. He decides he has to kill the horse now, because it had accepted another master. His father warns him that you can't be a good king with that kind of attitude (i.e. killing anyone and/or anything that doesn't go your way). Alexander pretty much ignores the advice, and there are consequences in the long run for him....

Tabletop Games

 * In the Mutants and Masterminds RPG, you can take a power feat called Restricted for your devices that does this.
 * In Champions, when a power is purchased through a Focus (an item required for the power to function), the purchaser has the option of defining the Focus as "keyed" to the character whom it's bought for. In that case, if an enemy gets ahold of the Focus, he can't use it against the character—but the character's allies can't use it, either.
 * Dungeons & Dragons
 * Intelligent weapons greatly prefers to be wielded by characters of the same alignment as them or a close one, and can refuse to use their powers for people who don't agree with their goals. If someone of an opposite alignement picks up such a weapon, it will likely give the "painful zap" response, the amount of damage depending of the weapon's ego score.
 * Some other magic weapons (which may or may not be intelligent too) have restrictions on the classes or races that can use them. Weapons forged for paladins, for example, will only bestow their full power when wielded by a paladin and no other class, even if Lawful Good. In the hands of unfitting characters, such items will at best perfom like average magic weapons, or be non-magical, or could even act like cursed weaponry.
 * The 3.5 rules introduced the Legendary Weapons. Those magic items only bestow a fraction of their powers to ordinary adventurers; to gradually unlock their full potential, a character must adopt the appropriate "Scion" Prestige Class and devote most of his or her career advancing in this class.
 * Warhammer 40,000 Roleplay series has lots of things (from some expensive safes to high-end sniper rifles officially issued by Imperial powers) equipped with "gene-lock", which is rather hard to change even for those with right skills.
 * In Rogue Trader "Loyalty Spirit" is even available as a weapon upgrades - an electronic lock, which may be based on voice recognition, derm-print, gene-scan or some lost ancient method, in the order of decreasing Availability and increasing difficulty to bypass or remove ("arcane" ones are Unique and unbeatable). Some signature gear of the Temple Assassins have genelock harder to crack than normal - we may assume that in this case difficulty is quality, and Officio Assassinorium, of course, can have the best when it wants.

Video Games

 * In Kingdom Hearts, Sora is the Keyblade's chosen wielder, and usually refuses to even remain in someone else's hands for very long. It can be quite fickle, however, especially when Sora is in the dumps.
 * Similar to the Real Life entry below, most weapons in the Metal Gear Solid series are programmed to only work for the person that it was issued to. Originally used to justify your inability to loot an automatic rifle off every mook you kill, it becomes a major plot point in the 4th game.
 * The Mani Katti in Fire Emblem: Blazing Sword will only permit itself to be used by Lyn. A bandit who had tried to steal it earlier couldn't even remove it from its scabbard.
 * Quest artifacts in Nethack will hurt you if you're not the right class. (Every class has its own quest and artifact, but you can use wishes to get others.) Picking it up, wielding, wearing or using it results in a painful shock that can even kill you on lower levels. (This is NetHack, after all.) If your alignment does not match the item, it will even refuse to let you pick it up!
 * Many, many items in the various BioWare games (and other similar RPGs) are only usable by certain classes or characters. Especially notable is "Spellweaver" in Dragon Age Origins, a sword that can only be wielded by an Arcane Warrior.
 * In Knights of the Old Republic II: The Sith Lords, made by Obsidian Entertainment, the player will find a lightsaber crystal called "Insert Player Name Here's Crystal" that only the player can wield. As you level up, and get Karma Meter points, you can ask Kreia to "tune" the crystal, increasing it's stat bonuses in different ways, based on how you are playing the game. It's unclear what exactly effects it, but it's color will change (white, grey, black) with your karma values.
 * In the AGD Interactive King's Quest II Fan Remake, Neptune's trident is stolen by the evil Sharkees, and King Graham is promised the Water Gem in exchange for getting it back. Sneaking into the Sharkee Palace, Graham comes across the Sharkee King trying intensely to the trident to work, but to no avail, as it is enchanted to only obey people of noble blood and good will. The Sharkee King also knows of this enchantment and it angers him, as he, being the ruler of the Sharkees has the "noble blood" part covered, and since he obviously has the greatest will of all underwater creatures, wielding the trident should be a cinch for him. As Graham steals it back, he has no problems with using it for his own protection as he is a king after all and has a good will.
 * "Moonthril" weapons in Kingdom of Loathing are very time-consuming to obtain but extremely powerful. Unfortunately, they bind to their original owner and vaporize when their owner dies... and since the New Game+ involves reincarnation they are just not worth it.

Western Animation
"Timmy: Wanda, I wish you were a Reset Watch! (Wanda glares at him) That only works for me!"
 * Lampshaded and Discussed in an episode of The Fairly OddParents: Timmy wishes for a "Reset Watch" that lets him travel back in time. After Vicky gets a hold of it, Wanda recommends that whenever he wishes for gadgets like that, he should add the requirement that they only work for him.


 * Ultimately, this is how he gets back the other watch -- he claims the Wanda-watch to be much more powerful, tricking Vicki into switching them only for her to find out she can't use it before suffering from a large amount of Amusing Injuries.


 * By all appearances, the Omnitrix in the Ben 10 series: It doesn't work for Vilgax when he steals it in an episode of Alien Force, and even after it gets Ret Conned to being easy to remove from its host, Azmuth is still only reluctantly resigned to letting Ben keep it. It can only be that he knows that the watch chose Ben and won't work (at least as well) for anyone else. He originally intended it for Ben's grandfather Max, but there's no rule saying an Empathic Weapon's choice in owner can't conflict with its creator's choice. Although the first case was the Omnitrix reconfiguring.
 * In an episode of Samurai Jack, Aku manages to disarm Jack and tries to kill him with his own sword. It harmlessly bounces off of him because it cannot harm anyone who is pure of heart.
 * Adventures of the Galaxy Rangers: While the other three Mechanical Horses of the Galaxy Rangers are okay with having a teammate other than their "designated" one ride them (Doc and Niko trade off on Mel and Voyager several times), Triton is very forthright with the fact that only Shane can ride him, only making an exception on Shane's explicit orders.
 * The Autobot Matrix of Leadership from Transformers could be said to be like this. While it is said that the Matrix would "light their (the Autobots') darkest hour", it should be noted that the Matrix chose to empower Hot Rod (thus turning him into Rodimus Prime) and not Ultra Magnus, which may mean that it still only responds to certain individuals and not just any Autobot.
 * The Hearts of the World (Candracar, Meridian, Zamballa, Earth) from W.I.T.C.H. are like this. They can only be used by a chosen person, can only be given up willingly by said chosen and if it's taken by force, it returns to them. Unfortunately for Elyon and Kadma (bearers of the Heart of Meridian and Zamballa, respectively), Nerissa used this to her fullest.
 * In Thundercats 2011, Only the protagonist Lion-O appears able to utilize the Sword Of Omens' "Sight Beyond Sight" Though others may take custody of the blade, it's enchanted against "being touched by the hands of evil," which appears to be a failsafe against Big Bad Mumm-Ra's using it.
 * Felix the Cat's transforming "Magic Back of Tricks" only works for him.

Real Life

 * Several firearms companies are experimenting with technology to make guns that won't fire unless they're held by the owner. Such technologies include code keypads, magnetic or RFID rings, palmprint scanners, and subcutaneous embedded chips.  They haven't caught on yet, because they also have a non-negligible probability of malfunctioning and preventing the owner from firing the weapon.
 * Invoked in Spanish Salvavirgo (Virginity Guard) knives, some of which have inscriptions like I Guard My Mistress.