History Main / TwoSiblingsInOne

* UsefulNotes/{{The Bronze Age|OfComicBooks}} Creator/MarvelComics character [[http://marvel.com/universe/3-D_Man 3-D Man]] was the soul(?) of a dead brother, brought back to life by the live brother when concentrating through his glasses.

* ''{{TabletopGame/Warhammer}}'' has Vilitch the Curseling, who began life as a feeble and oppressed shaman's apprentice forever in the shadow of his brother Thomin. Vilitch's bitter prayers were answered by his patron god Tzeentch when he was magically fused to the shoulder of his hulking warrior-twin and able to take control of their conjoined body. Thomin is now a near-mindless thrall... at least until the End Times, when [[spoilerTzeentch reverses the curse, with Thomin in charge and Vilitch the slave]].

This occurs when a character's sibling dies and the character absorbs their soul, or the dead may force their LifeEnergy on to their sibling. The rule of "two souls cannot control a body at the same time" usually applies and the siblings will switch control over the body. The original owner of the body is usually in charge, but the dead sibling will take control at key moments. Usually accompanied by friends of the 2-souled-twin saying he/she is NotHimself. In most cases when the inhabiting sibling is in control, a distinct feature will let the audience know. This can range from MindControlEyes, to a [[{{ColorCodedForYourConvenience}} colored]] [[{{BattleAura}} aura]] that appears around the character, in some cases the voice will also change.

* In ''Manga/{{Basilisk}}'' the {{Big Bad}} of the group apparently absorbed his twin brother. His brother is still alive, so to speak, as a monstrous symbiote who gives his brother immense regeneration in return for surviving freakishly. This also counts as squick, since said symbiote is only able to speak through his brother's ripped throat.

* In ''Anime/LeChevalierDEon'', Lia forces her soul on to D'Eon so that she can take revenge on her murderers.

* Creator/MarvelComics' ''Brother Voodoo'' with Jericho (living) and Daniel (spirit) Drumm. Daniel could leave Jericho's body to possess other beings.
* Doctor Occult and his companion Rose Mystic of DC comics are this, unless they aren't. They either tell different false versions of their origin, or all the versions are true in some sense; with mystic characters it's hard to tell. In some versions of their backstory, Doctor Occult absorbs her soul when she's dying, and they share the body, switching forms based on which one is in the figurative driver's seat. Whether she's his fraternal twin sister, lover, partner, fellow graduate of a mystic academy, and/or some combination of these varies with the retelling. In other versions, they're the male and female aspects of the same being (and in some versions, they started out as the first, and eventually blended so thoroughly they became the second). If DC had a mystic Facebook, their relationship status would definitely be "Complicated."

* In ''Film/WonderMan1945'' Edwin Dingle's late twin brother Buzzy Bellew possesses him as "encouragement" to help put the perpetrators of Buzzy's murder behind bars.

* ''Literature/AngelaAndDiabola'', this is how the SurprisinglyHappyEnding comes about. When EvilTwin Diabola dies, good twin Angela absorbs her evil and becomes an ordinary, basically good yet flawed person. The change is signified by one of Angela's blue eyes turning green, like Diabola's were. This is justified by the fact that apparently, Angela and Diabola were always meant to be just one person, but that some "cosmic accident" caused them to be born as a good twin and an evil twin instead.

* In ''Distant Waves'', Amelie and Emma, after [[spoiler:Emma dies of hypothermia]].

* In ''Literature/TheLockedTomb'' series, a necromancer attains Lyctorhood (which grants immortality and extreme power) by killing their cavalier (a sort of personal bodyguard) and consuming their soul. This isn't usually a sibling bond, but there are a few instances in the series in which the specific trope is invoked. In ''Literature/GideonTheNinth'', Coronabeth [[spoiler: (who isn't actually a necromancer but is posing as one)]] is devastated when her twin sister Ianthe [[spoiler: becomes a Lyctor by consuming their cavalier's soul ''instead of hers'']]. In the sequel, ''Literature/HarrowTheNinth'', we learn that Augustine the First did this to his brother Alfred, who served as his cavalier (it doesn't explicitly say they were twins, but it doesn't say they weren't, and since he becomes something of a mentor/foil to Ianthe, it may be implied).
* Played with in ''Literature/MyNextLifeAsAVillainessAllRoutesLeadToDoom''. [[spoiler:The character that everyone refers to as Sirius Deek is actually his illegitimate half-brother Rafael Walt. Sirius' mother coerced a man into performing a dark magic ritual and transferring Sirius' consciousness into Rafael's body. Rafael did end up inheriting all of Sirius' memories, though he still effectively remained himself, and he's been pretending to be Sirius for years to avoid being killed.]]

* This was the basic premise, with a twist ending, of the short-lived Creator/{{NBC}} series ''Series/DoNoHarm2013''.

* Warhammer has Vilitch the Curseling, who began life as a feeble and oppressed shaman's apprentice forever in the shadow of his brother Thomin. Vilitch's bitter prayers were answered by his patron god Tzeentch when he was magically fused to the shoulder of his hulking warrior-twin and able to take control of their conjoined body. Thomin is now a near-mindless thrall.

* French comic ''La Rose Ecarlate'' has the twist that PolarOppositeTwins [[TheIngenue Artemis]] and [[{{Sadist}} Apollo]] actually share Artemis's body unbeknownst to her, which in turn means that she is prone to feeling disoriented and confused once she comes back to herself.

* The big twist of ''Film/{{Malignant}}'' is that [[spoiler: Madison's murderous twin brother Gabriel doesn't just exist "inside her head", he ''literally is inside her head''.]]

* The big twist of ''Film/{{Malignant}}'' is that [[spoiler: Madison's murderous twin brother Gabriel doesn't just exist "inside her head", [[ParasiticTwin he ''literally is inside her head'']].]]

* The big twist of ''Film/{{Malignant}}'' is that [[spoiler: Madison's murderous twin brother Gabriel doesn't just exist "inside her head", [[ParasiticTwin he "literally is inside her head"]].]]