When twins are portrayed as inherently having a deep, almost mystical or magical connection with one another, far stronger than the bonds between non-twins, even when the setting doesn't call for such a fantastical element, it's this trope. This shows up in a wide variety of ways, like speaking in unison and Finishing Each Other's Sentences without prompting. Twins will know things about each other (their location, what they're doing) they should have no way of knowing or may sense when the other is hurt or in danger in a way that goes far beyond mere intuition. In some stories, it even escalates into full-on Synchronization, with the twins sharing the same wounds.
If they've teamed up in a conflict, they will be a huge asset to their side, their uncanny connection allowing them to work together better than any duo or team, though their Undying Loyalty to each other may sometimes push them to prioritize each other over the group or cause. When on opposing sides, their confrontation is often fated and unavoidable, with heavy doses of The Only One Allowed to Defeat You and Only I Can Kill Him thrown into the mix, even when it's explicitly not personal. It is also common for this connection to be depicted as romantic and sexual in nature or to become such due to the sheer intensity of the feelings.
In more fantastical settings where superpowers and abilities are widespread, the connection will manifest in twins having complementary abilities (if not the same one): they may serve as living Amplifier Artifacts for one another, increasing their abilities far beyond what someone without their bond can manage. Or they might be weak, underpowered, or totally useless until they are together, at which point their ability becomes far greater than the sum of its parts.
The idea of a mysterious, powerful, and exclusive bond between twins can also show up in the twins themselves being portrayed as or thought of being "special" entities to be revered and feared. This portrayal is actually quite common across many cultures and can be found in the beliefs and mythologies of ancient civilizations around the world. Note that "special" does not mean "positive": for as many superstitions about twins as a sign of immense luck and fortune as there are, plenty view twins as harbingers of disaster and ruin, if not outright evil themselves.
Regardless of how it shows up in a story, the point is that the twin connection in of itself is used to explain or justify why these siblings are unique.
This is a Super-Trope for several Twin Tropes as the premise they are built on, specifically: One Twin Must Die, Single-Minded Twins, Superior Twin Teamwork, Twin Telepathy, Twin Banter, and Wonder Twin Powers.
The Maybe Magic, Maybe Mundane nature of this trope means that for clarity's sake, restrict examples on this page to those in which the twins or their abilities are considered extraordinary In-Universe. For example, in a world of superpowered beings, Twin Telepathy examples should not be listed here unless it is considered exceptionally strong or unique in-universe because of the twin bond. In works that skew more towards adhering to the laws of Real Life however, Twin Telepathy of any sort counts.
- In Volume 8 of Arisa, when Tsubasa is hurt, hospitalized twin sister Arisa flatlines. Tsubasa later lampshades this trope by saying you should not underestimate the bond between twins.
- Ceres, Celestial Legend: Subverted and deconstructed to horrifying effect.
- At the start of the story, twin siblings Aki and Aya Mikage are revealed to be hosts for the spirits of Mikage family progenitor Mikagi and his reluctant wife/powerful celestial maiden Ceres, respectively. They soon learn it's not because they are twins, but because they are near genetic duplicates for the two due to Royal Inbreeding. Possession by Mikagi is considered an auspicious sign by the Mikage family, as he is prophesized to lead the family to continued prosperity, whereas possession by Ceres is considered a Doom Magnet, so the family typically kills the host. Because Aya and Aki are twins, this also creates an inadvertant One Twin Must Die scenario.
- Before they realize they are hosts, Aki and Aya have a close, but very normal sibling relationship. However, that changes once their host status is revealed because Mikagi is still romantically and sexually obsessed with Ceres, does not care that his vessel is the brother of her vessel, and has no issue with acting on his desires. While both Aki and Aya are disgusted by this, Aki has a hard time keeping his platonic love for Aya separate from Mikagi's feelings for Ceres the more he gets possessed. In fact, his increasing shame regarding those feelings makes Aki's consciousness retreat more and more, which only makes it easier for Mikagi to gain control over his body. Aki's anguish shows just how awful it would be to be irrationally and inexplicably attracted to one's own twin.
- Fushigi Yuugi has Amiboshi and Suiboshi who exhibit both Twin Telepathy and Synchronization: when Amiboshi "dies," Suiboshi can sense it. They are able to write messages to one another on their skin. For example, Amiboshi writes something on his left hand with his finger, and the message appears on Suboshi's left hand.
- Deconstructed in Mars (1996). Rei and Sei were exceptionally close even from a young age, however this bond is rarely portrayed as healthy by other characters, since Sei openly treated Rei as a Living Emotional Crutch and in response Rei became a Knight Templar Big Brother who would go berserk on anyone that seemed to hurt Sei. As they get older, Rei begins to resent this dynamic and tries to create some distance between them by pettily revealing to Sei the nature of their parentage. Sei does not take it well and Rei spirals into destructive sociopathy blaming himself for Sei's death. It's only by meeting Kira that he even begins to get better and even then, it's an uphill battle.
- In the manga of Ouran High School Host Club, Hikaru and Kaoru's character arcs revolve around allowing others inside the world they've created around each other. Flashbacks show the twins as being reclusive and exclusive, believing that no one besides each other can fully understand them. It's not until Tamaki and Haruhi come around that they begin to try to let others see the real them and not the brotherly act they put on to push people away. During the test of courage chapter, they seem to manifest Twin Telepathy out of nowhere when they get separated and Kaoru gets locked in a classroom. Hikaru somehow manages to find Kaoru and explains that he had heard his twin's voice telling him where he was, even though Kaoru had no way of telling his twin his whereabouts and Hikaru could not have found out through someone else.
- Tsubasa -RESERVoir CHRoNiCLE-: Fai and his twin brother were imprisoned and emotionally tortured as children because in their country of birth Valeria, twins are considered a bad omen.
- Misaligned Gemini: By some, split-spark twins are revered and treasured for being a "miracle of Primus". By others, they're despised and shunned for being "abominations" that spit in the face of Primus. Split-spark twins are a rarity on Cybertron and no one knows how a spark divides into two bots. Some think it's the will of Primus, others believe twins are an omen of bad luck. After Exarchon, negative stigmas against twins (calling them violent, insane, unstable, etc.) became the norm and many still hate split-sparks in the present day. Sunstreaker and Sideswipe are careful not to let anyone know they are split-spark twins because of this.
- The Phantom Twins: The premise of the series is this trope. The two main characters are twins who possess the same ghost powers, and have a very close bond with each other.
- Under Strange Stars: Twins Elladan and Elrohir have a very strong bond. Even from leagues away, they can sense each other's feelings, tell if their brother is in danger, etc. In fact, their connection was so strong as children that their parents feared they'd become one person in two bodies. To avoid this, they decided to send Elrohir to live with his grandparents in Lorien for a year, but the party was attacked on the road and Elrohir was kidnapped, kicking off the events of the story.
- Subverted in Avengers: Age of Ultron with the Scarlet Witch and Quicksilver. They are classified as "enhanced individuals" because of their powers and are given the codename "The Twins" in the film teaser at the end of Captain America: The Winter Soldier setting this trope up, but their powers are not a product of their twinness (they're the products of individual bioengineering and genetic experimentation) nor are their abilities particularly complementary. When Pietro dies, Wanda does instantly sense it from far away, but a reciprocal psychic link between the two hadn't been established before this point, so it's likely this has more to do with Wanda's individual telepathy than anything else.
- In Constantine (2005), Isabela and Angela were born with strong psychic powers, strong enough for both to be considered good vessels for Lucifer's son Mammon to inhabit. Other powerful characters in the film are either a halfling of some sort or derive their powers using exorcism tools, with the exception of Witch Doctor Papa Midnite.
- Alexandre Dumas's The Corsican Brothers about Separated at Birth twin boys has been adapted numerous times, including a 1985 TV movie titled The Corsican Brothers starring Trevor Eve as both brothers. Like the original, the boys can sense each other's pain despite being miles apart. A 1989 animated film adaptation similarly keeps this ability in.
- In Hellboy II: The Golden Army, Prince Nuada and Princess Nuala can read each others' minds and when one of them is injured, the other is injured as well.
- Downplayed in The Skeleton Twins. The film starts with Maggie standing over her bathroom sink, holding a fistful of pills seemingly preparing to Suicide by Pills. She is only stopped when she receives a phone call from the hospital informing her that brother Milo, who she hasn't spoken to in years, was there because he tried to commit suicide, too.
- In Star Wars, Luke and Leia have a connection despite having been Separated at Birth, which conveniently doesn't appear until a crucial moment in the second film. Though this may have less to do with them being twins as it does them having a familial bond on top of being strong in the force since Luke demonstrates a similar connection with his father.
- Separated at Birth twins John and Boomer in Twin Dragons realize when they meet as adults that when they are within a 100-mile radius from each other they will inexplicably start to respond to each other's actions. While Boomer is in the Bay of Hong Kong in a boat chase against gangsters, John, who's in a posh hotel by the beach, begins to feel and act as if he's being thrown around on a motorboat.
- Justified in Twins (1988), as Julius and Vincent are the products of genetic experimentation to produce the perfect child by fertilizing a single ovum with the sperm of six different men, Julius getting all of the desired genes and Vincent getting all of the leftovers. This technically makes Vincent Julius's twin, doppelgänger, and clone all at once! They experience both Twin Telepathy and Synchronization.
- Fraternal twins Wututu and Agasu from American Gods are split up and sold into slavery because the tribe they're born into believes twins to be magical beings, capable of cursing others. They also exhibit Twin Telepathy and Synchronization: when Agasu's arm is cut off, Wututu's arm withers and when Agasu later dies in the Haitian Revolution, Wututu can sense it. The narration notes how together they were strong, but apart they are just two scared children, though as Wututu grows to become a woudoo priestess, it's not quite Wonder Twin Powers.
- The Corsican Brothers featured twin boys born to a nobleman during wartime. Due to a strange prophecy, one baby was separated and sent away to a different home. Despite not growing up together, the twins seemed to share an unusual bond and be able to sense each other's pain.
- In the Dragonriders of Pern short story "Ever the Twain", the bond (emotional/mental/possibly both since psychic power is a real thing in the setting) between the fraternal twins Nian and Neru is so strong that it actually prevents the dragons from sensing Neru's potential as a candidate for Impression. The strength of their bond is such that Nian's concern for Neru when it seems like he failed to Impress is so strong that she doesn't even notice when she Impresses the newborn queen Quinth, who has to knock her down to get her attention.
- In Expiration Date, Pete and his twin sister frequently know what each other is thinking and can finish sentences in unison. It's explicitly stated that, despite the psychic phenomena going on in the rest of the novel, they don't have a psychic link; they just know each other really well.
- Star Wars Legends: Jacen and Jaina, Han and Leia's twins, have a "twin bond" which goes much deeper than the usual connections between Force-users. Notably, the telepathic bond second to their own is the one they share with their younger brother. Part of the reason the Yuuzhan Vong become so obsessed with Jacen and Jaina is precisely because they're twins, which according to the Vong's religion means that they should be destined to duel each other to the death, yet fight together.
- Elizabeth and Jessica Wakefield are shown to have instances of Twin Telepathy in the Sweet Valley High series and it only seems to manifest at plot-relevant moments. Lampshaded at one point, when Jessica and older brother Steven are separated from the rest of the family during an earthquake, and Steven asks Jessica if she can use her telepathy to sense if Elizabeth is okay. Jessica snaps, "It's not like a psychic telephone hotline I can dial up whenever I want to."
- Alex and Cam in TWitches are powerful Polar Oppposite Twin witches whose births were prophesized generations ago. They have opposing elemental abilities and their magic gets stronger when they are together.
- In Wings of Fire, it is extremely rare for SkyWing twins to hatch from the same egg, making any that do considered special. One of them is constantly Wreathed in Flames (known as firescales), while the other has no fire at all.
- The Babylon 5 verse already has non-twin telepaths. The Centauri, however, place special value on telepathic twins, using specially-trained pairs raised from birth as the Emperor's personal communication system. The Emperor seems to normally have two sets of twins, and one from each pair always accompanies the Emperor when he travels while the others remain in the palace. This provides instantaneous communication and awareness of the Emperor's situation independently of any technology that could be hacked or jammed.
- Game of Thrones: For much of the series, the relationship between Jaime and Cersei is characterized by both as being particularly deep and this trope is implied to be part of the reason behind their Twincest. Several times they've both argued that non-outsiders who try to judge them simply are not able to understand the depth of the bond between them. This comes to a head in Season 8 when Jaime, who recently turned his back on Cersei to fight the White Walkers with his brother and Brienne, decides to give it all up to return to Cersei and die by her side.
- In The Haunting of Hill House, Hugh Crain gives Luke a bowler hat and asks if he's happy. When Nell replies for him, Hugh asks how she knows, to which she replies with a shrug that "it's a twin thing." Later on, she accurately guesses that he's scared because she feels it, too. On separate occasions, they also exhibit being able to experience what the other is feeling, such as Nell's ankle going crazy when Luke broke his, and Luke having a sore neck and feeling cold all over despite the hot weather due to Nell hanging herself and dying at the exact same moment.
- Fraternal twins Kate and Kevin on This Is Us have occasional moments of knowing each other's emotions and thinking alike. When Kate is hospitalized on Christmas Eve with appendicitis, Kevin is seen in the waiting room clutching at his side while she's being operated on.
- The Vampire Diaries: The aptly named Gemini Coven is one of the most powerful witch covens in the series. In this coven, twins are always first in line to become the leader and those chosen undergo a ritual called The Merge, during which the twins merge their consciousness and magical ability. The weaker of the twin's consciousness fades and they die, leaving the remaining twin doubly empowered. Though it is possible for non-twins to do The Merge, as shown through Luke and Kai's experience, merging between non-twins weakens the effectiveness of the ritual and the remaining sibling will slowly die over time.
- Classical Mythology: Castor and Pollux are an interesting case as they are twin half-brothers, born from the same mother but with two different fathers. Pollux's father is Zeus and Castor's father is Tyndareus, King of Sparta. The brothers' deep bond with each other is immortalized in the tale of Castor's death. As Castor had no divine lineage, he did not share either the immortality that Pollux had or the ability to ascend to Olympus upon death (depending on whether Pollux is interpreted as a non-mortal in the text). Thus, when Castor is killed by his cousin Idas in a botched revenge scheme, Pollux asks his father Zeus to share his immortality with Castor. This allowed them both to go between Olympus and Hades and they were later immortalized in the sky as the Gemini constellation.
- Egyptian Mythology:
- Nut and Geb, the dualistic twin deities of the sky and earth, respectively. In one version of the creation myth, the depth of their bond begins in the womb, during which it is said they were born holding each other. Ra had to separate the two using air, which gave the twins their domains, however it did not curb their bond as the two remained lovers. They are considered complementary symbols that complete each other, forming a whole.
- The famed lovers Osiris and Isis were also twin siblings (quadruplets actually, in addition to their siblings Seth and Nephthys who were also lovers). Some interpretations attribute the "holding each other in the womb" story not to Osiris and Iris's parents Nut and Geb, but to their birth instead.
- Mesopotamian Mythology: Some interpretations of Mesopotamian texts not only see Inanna and Utu as fraternal twins but also as having a bond so close that it may or may not have been incestuous.
- In Yoruba Mythology, the Orisha Ibeji (or Ibeyi) is depicted as a pair of twins representing joy and happiness. Twins in Yoruba culture are considered magical; when one twin dies, it is a sign of misfortune for the parents and the society they are members of. To counteract this, a wooden Ibeji that represents the lost twin is carved and kept.
- In Warhammer, Tyrion and Teclis, champions of the Asur, are both twins born into the line of Aenarion the First Phoenix King. The Blood of Aenarion is rare, and twins born among elves are even rarer than that, so their birth was considered especially auspicious. They fit the complementary mold. Tyrion became an expert warrior and military leader, fit and strong, charming and diplomatic, but with a cold brutality just beneath his surface. Teclis was sickly and weak, but became a singularly skilled archmage, with an intuitive grasp of magic, a genius mind, and an aloof and acid attitude, but with a sympathetic and understanding heart.
- In Dark Tales: The Fall of the House of Usher, based on the Edgar Allan Poe short story of the same name, twins Roderick and Madeleine Usher have a strange bond that causes them to feel one another's pain. A doctor who studies them determines that injuring one will cause the other to bleed, and their connection to each other also prevents them from straying very far from their ancestral home. The game opens with the detectives being summoned to find Madeleine, as her disappearance could be life-threatening to both herself and her brother.
- Death Stranding: Mama and her twin sister, Lockne, used to be able to hear each other's thoughts, until Mama was caught in the explosion of a hospital she was supposed to give birth to Lockne's and her husband's baby. Mama actually died in that blast, but her body was kept alive thanks to being tethered to Lockne's deceased daughter's soul. Mama, terrified of Lockne finding out that her daughter died, cuts off all contact with her, making Lockne think that Mama just took her daughter and ran off. During the course of the story, Mama realizes that what she did was wrong, and asks Sam to cut the cord connecting her and Lockne's daughter. Mama slowly starts to die, but thanks to Sam, she manages to reunite with her sister and apologizes to her before her death. When Mama passes on, her spirit fuses with Lockne's, with her saying that they were always one person, just in two separate bodies. They are the only known in-universe example of this ever happening.
- Fatal Frame II might as well be called Twins Are Special: The Game as the vast majority of the plot revolves around this trope. The mysterious Minakami Village that twin sisters Mio and Mayu find themselves trapped in has several rituals to appease the Hellgate it sits on top of, most important being the Crimson Butterfly Ritual in which one twin must kill the other, whose body is used as a human sacrifice. Why? Because of the belief that twins are actually one person born in separate bodies, and therefore are unnatural, and the death of one allows their spirits to become one again. The ritual does work, but the peace is only temporary, requiring the ritual to be performed every ten years and Mio and Mayu are next in line.
- Guilty Gear XX: The town Bridget was born and raised in believes that identical male twins will bring about misfortune and the superstition runs so deep that the younger twin must be either put up for adoption or put to death.
- Alexia and Alfred Ashford from Resident Evil – Code: Veronica are both this trope played straight and a bit of a subversion. On the one hand, they are in love with each other, with what seems like just Incest Subtext from Alexia, as Alfred serves as her Morality Pet, becoming fullblown overt romantic and sexual obsession from Alfred. On the other hand, only Alexia was created with the explicit purpose of inheriting Veronica's intelligence and power; Alfred is merely a byproduct of the cloning process. Thus, Alexia can mutate and transform while Alfred is nothing more than a Psychopathic Manchild, heavy emphasis on the psychopathic. In either case, the fact that they are genetically identical clones experimented on from birth justifies their unique bond and powers.
- There are several bosses in World of Warcraft that hinge around a twin theme. They tend to have identical (or complementary) abilities and share a single health pool. Oftentimes the encounter is staged such that you have to kill both of them within a short time window (say, fifteen seconds) or the dead one will resurrect and you'll have to start over. Another common mechanic is that when one twin dies, the other inherits their twin's magical abilities.
- Lady Sacrolash and Grand Warlock Alythess are collectively known as "The Twins" encounter in The Sunwell.
- Eydis Darkbane and Fjola Lightbane are a Yin-Yang themed pair of twin Val'kyr in the Crusader's Coliseum.
- Morchok and Kochrom (see what they did there?) are completely identical — they even have the same move set. Kochrom appears only in the heroic version of Dragon Soul.
- The original twin boss fight in WoW, of course, is the Twin Emperors (Vek'lor and Vek'nilash) in the Temple of Ahn'Qiraj. One is immune to physical damage, one immune to magic, and if they're standing close enough to one another they heal constantly.
- The Throne of Thunder raid in Mists of Pandaria features Suen and Lu'Lin, the Twin Consorts of the Thunder King.
- Unsounded: The Gods are believed to be two sets of twins, so twins are sacred in the Gefendur religion. Temples pay handsome fees to adopt twins, who are raised to adulthood in comfort, after which the younger one is sacrificed and the older is inducted into the priesthood.
- The Loud House: While Lola and Lana usually avert this, in "Training Day", it's revealed that one twin can always smell where the other one is. So can Stella's pet rabbits Jazzy and Snazzy, who are brothers from the same litter (though it isn't revealed if they have any littermates).