The Changeling is a daemonic Horror of Tzeentch who epitomises the Lord of Change's love of sowing discord and distrust, and his perverse sense of humour. Tzeentch long ago bestowed upon the Changeling a doppelganger's ability to assume any shape, from that of the tiniest insect to the largest Greater Daemon. The Changeling carries out practical jokes in both the Realm of Chaos and realspace, always intended to bring about the constant change so beloved of his patron. The only shapes that the Changeling cannot assume is that of Tzeentch and his own, for he has long forgotten his original form, and desperately seeks to regain this knowledge through any means necessary. Only the Great Schemer knows the Changeling's true form, and he will never reveal it so as to keep his favoured pawn under his control.
The most accomplished trickster amongst Tzeentch's daemons is the Changeling, the embodiment of the Great Schemer's need to meddle and deceive. The Changeling is possessed of a supernatural ability to assume the shape of any other creature in the universe with unfailing precision. He is the ultimate doppelganger; there is no form that the Changeling cannot duplicate, no mannerism he cannot adopt. From small animals to towering alien monsters, common citizens to Planetary Governors, the Changeling has impersonated them all. Indeed, the only image that the Changeling is unable to replicate is that of Tzeentch himself, for the Great Schemer will not tolerate any being mimicking his identity.
The Changeling is a restless and mischievious daemon who roams the galaxy and the Warp alike, playing devastating practical jokes upon the unwary. He lives to sow discord and conflict, and delights in breeding mistrust and confusion. Many lords throughout the galaxy have made unusual and disastrous decisions, only later to deny that they were ever even there at the time the decision was made. On many battlefields, a great hero has fought an opponent that was his mirror-image, his comrades unable to tell the difference between the two until it was too late.
It was the Changeling in the image of the sainted Lord Solar Commander Macharius who ordered the retreat on Goranna just as the real Imperial Warmaster was directing his forces forwards on the front lines. In the guise of a lowly Gretchin, the Changeling made a few alterations to Warboss Gitsmasha's favoured Megashoota -- a fact that only became apparent when it next fired, blowing Gitsmasha and his retinue of Nobz to tiny green pieces.
On one occasion, the Changeling took the shape of a Keeper of Secrets and answered the summoning of an Imperial Commander whose vast palace was besieged by the vengeful Dark Angels Space Marines. The Changeling traded the souls of the desperate man's daughters for a "powerful artefact" which in the fool's own words "would put an end to the siege." The moment the commander activated the device, the shadowy forms of several Deathwing Terminator Squads materialised around him, locking onto the device he was holding in his hands -- a Teleport Homer the Changeling had stolen from the Ravenwing. The siege was indeed soon over while the Changeling dallied with the man's pretty scions.
The Changeling's pranks are not limited to the mortal realm. Countless wars have been started between the Chaos Gods by the Changeling's practical jokes, such as when he cut Slaanesh's beloved hair with a stolen Hellblade whilst the Dark Prince slept, or the time he snuck a trio of Nurglings onto the Skull Throne, creating a hideous noise and an unholy mess the next time Khorne sat down.
So many times has the Changeling altered his appearance and shape that even he has forgotten what his original form was, and so when not in the guise of another being, he cloaks himself in a long shroud from the gaze of others. It is whispered by Tzeentch's other Heralds that beneath his cowl, the Changeling is in a state of constant flux, randomly changing between all the faces he has assumed in the vain hope of rediscovering his original features. However, only the Great Schemer remembers the Changeling's true form, and he keeps the secret for himself so as to forever keep the Changeling under his control.
- Black Crusade: The Tome of Fate (RPG), pg. 12
- Codex: Chaos Daemons (6th Edition), pg. 44
- Codex: Chaos Daemons (4th Edition), pg. 54
- White Dwarf 368 (UK), pg. 7
- Fateweaver (Novella) by John French