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A Wechselbalg (VEKH-sel-balkh; plural: Wechselbälger; Ger. "changeling") is a Doppelgänger-like Wesen that appeared in The Killing Time.


According to Grimms' Dictionary, Wechselbälger were the supposed explanation in the middle ages for birth defects and mental developmental disorders. Early Germans believed a demon had exchanged their real child for a Wechselbalg, which was the child of the Devil and any of the female spirits in the wilderness. Even in the late 1800s, many Europeans still assumed any disfigured child with a severe mental disorder was a Wechselbalg. It was said that Wechselbälger had fat heads, fat bodies, and skinny legs, and did nothing except eat and drink. They were considered ill-mannered and aggressive. The real human children were assumed to have been kidnapped and raised by dwarves in the mountains. Exorcists were said to have been able to make the original child reappear in a Wechselbalg's place by either making it laugh or by being especially cruel to it.

The legends about Doppelgänger stemmed from reports of encounters with Wechselbälger. According to the legend, if you met a person who looked like you, something bad was about to happen. That "something bad" was that you would die.


Wechselbälger are rare enough that even if a kill is carelessly left for discovery by Kehrseiten, the odd mass of dissolved tissue does not even give investigators a clue of the suspect.


Wechselbälger are featureless and genderless, and look like a person made from a silvery liquid. They have 3-inch black retractable nails on each finger and thumb, which they use for killing their human victims. When the nails are pressed into the skin, the prey begins dissolving into a shapeless mass of tissue. This dissolving process is called Auflösen (Ger. "dissolve"). During the kill, the Wechselbalg absorbs its prey's entire identity, taking on its shape, voice, donned clothing, gender, and even knowledge. This makes a skilled Wechselbalg an effective identity thief.

It appears to be made almost entirely of woge-hormone, and this requires the Wechselbalg to keep itself well-hydrated by drinking lots of fluid. ("The Killing Time")

The Wechselbälger's true appearance is visible only during a kill, and only to a Grimm. It has no distinct odor detectable by a Blutbad, making it difficult to track. ("The Killing Time")


The Wechselbalg's body eventually begins to decay, signaling the need for a new body. The amount of time a body lasts before decaying varies, averaging around five years. The Wechselbalg must find a new body in order to stay alive.

Transition from one body to another involves multiple steps:

  1. Transitional state (visible only to Grimms) - The body loses all distinguishing features and becomes a liquidy quicksilver form.
  2. Woge - Digital spines emerge.
  3. Attack - The victim's flesh is punctured with the spines and injected with an anaesthetic
  4. Transformation - The Wechselbalg assumes its new identity. The outermost layer of skin is shed and takes on the form of the victim's clothing, though pocket contents cannot be duplicated. Physical appearance, stamina, memories, and knowledge are among the traits assumed.
  5. Auflösen - The victim dissolves into a shapeless puddle of basic proteins.

As the Wechselbalg gets older, the time it can remain in one form lessens, with a particularly old Wechselbalg only able to remain in its new form for a few hours before its body began to noticeably fall apart.

Excerpts from the Grimm diariesEdit

Wechselbalg. German for changeling. These Wesen are born without identities of their own and exist by periodically assuming the identity of others. They take on their victim's appearance, personality, and memories, reducing the victim into basic proteins in the process.

The Wechselbalg is known to duplicate only humans. It is unclear if this is a biological restriction or a preference. While the Wechselbalg has no true appearance of its own, it does have a transitional form that resembles fluid quicksilver. It uses retractable needle-like spines to absorb a victim's identity, and while the specifics of how the process functions remain unclear, it is believed that duplication is accomplished in a relatively short time.

Wechselbalgen are generally healthy and are immune to disease even while in human form. Their borrowed bodies do tend to show signs of wear and decay after a time, signaling the need for the Wechselbalg to seek out a new victim. The length of time a Wechselbalg can retain a specific form is uncertain, but it's believed that five years is the average, with ten years being the upper limit. As long as the Wechselbalg can find new forms to duplicate, it can conceivably live far longer than a normal lifespan.

Health concerns for Wechselbalgen include infection of digital spines if they are not cleaned regularly, loss of dermal elasticity-- especially as the time to seek a new host approaches-- and in their later years, Verfallserscheinung.

Treatments for spine infection and dermal non-elasticity have been omitted from this excerpt.

Verfallserscheinung: No treatment known.


  • Verfallserscheinung is German for "sign of decay" or "symptom of decline."
Wesen in Grimm novels
Primate Wesen Wechselbalg

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