This article is about the family seat and residence. For the noble lineage, see House Heterodyne. For other uses, see Heterodyne (disambiguation).

Castle Heterodyne (or as the Jägers say, der Kestle[1][2]) is the ancestral home of the Heterodyne family, and a character in its own right. Located in Mechanicsburg, it is built at the source of the River Dyne, from which it extracts the energy to power itself.

Intelligence and behavior Edit

Castle Heterodyne is essentially a giant immobile clank, equipped with, evidently, a copy of the personality of its creator (see below). One of its primary interfaces is located in the Heterodyne family crypt, though it has the limitation at that location of being unable to speak directly, but only through a human linked to it, one who has had his skull pre-equipped with specially-installed interface sockets.[3]

The Castle is able to physically reshape itself and manipulate (at a minimum) non-organic objects within its walls, a capability that is ornately demonstrated[4] by the part of the currently-fragmented Castle that is first to acknowledge Agatha as the new Heterodyne.

On three occasions so far, during other Castle-interactions with Agatha, the scene cuts away to show us three lights; it is strongly suggested that each light comes on in turn when an important stage in recognizing Agatha to be the new Heterodyne is reached: the first time comes when Agatha's voice is found to be similar to that of Lucrezia Mongfish, the second after a blood sample from Agatha is analyzed, confirming her to be of Heterodyne descent and the third, when the Castle gets hit by enough electricity (i.e. repeated massive lightning strikes) to restore most of its power.

Even when fragmented and only partially functional, the Castle's control and powers extend an unknown distance into the surrounding town.

History Edit

Creation Edit

As related by Ardsley Wooster Castle Heterodyne was originally built in 1042 by Knife, who seems to be the first Heterodyne to drink the water of the Dyne. Instead of killing him, as it was generally purported to do to imbibers, Knife found he liked the taste of the stuff and built his fortress on the spot.

This first fortress was accidentally destroyed by Egregious Heterodyne in his attempt to expand the flow of the Dyne, who considered the experiment a great success. Evidently, the Castle was rebuilt and destroyed two more times “before the present structure was erected in 1298” again according to Wooster . If Van uses the same dating system this structure took about ten years to construct . The Castle was first programmed with self-awareness in (perhaps) 1677 by Faustus Heterodyne, another of Agatha's mad scientist ancestors. Since then, it has been considered to be alive. Its charming personality — it thinks it has a sense of humor — is said to be a copy of his.

Attack Edit

Main Article: Attack on Castle Heterodyne

Nineteen years prior to the beginning of the Girl Genius narrative, The Castle was nearly destroyed in a massive explosion, presumed to be an attack by The Other. Many people were killed that night, including Agatha's infant brother Klaus Barry Heterodyne and the then-new seneschal (the son of Carson von Mekkhan).[5] It was the same night that Lucrezia Mongfish went missing.[6]

Subsequent History Edit

About four or five years later[7] a “professor from Transylvania Polygnostic University led a team of researchers inside” ... who were captured by the Castle and tasked with repairs.

Eventually, at some point after Baron Klaus Wulfenbach returned from his Lucrezia-imposed banishment and took over Mechanicsburg, the Castle released an assistant from the TPU team to procure food, tools, and more help. The Baron, ever able to apply the right monster to the right job, negotiated with the Castle, obtained the professor's release and proceeded to send the structure his most difficult and dangerous Sparky prisoners. This is considered the Empire's ultimate punishment detail, as the chances making it out alive again are extremely (but not impossibly) slim.

Such is the situation when Girl Genius opens.

In the Story Edit

Broken Castle Edit

Following Judy's instructions "Go! Get to Castle Heterodyne. It will help you." , Agatha travels to Mechanicsburg, speaks to the broken Castle via Carson, and enters the Castle in the guise of a (relatively) common prisoner. The same day, Zola "Heterodyne" also enters the Castle in a quest to usurp the family name as one of the public faces of The Storm King Conspiracy, though she plans to kill the Castle rather than repair it. They both begin to interact with the Castle's current crop of inmates, some of whom go on to play significant roles in Agatha's story; among the more prominent are head inmate Professor Hristo Tiktoffen and Agatha's newly (and unwillingly) anointed Chief Minion Moloch Von Zinzer.

It gets to be even more crowded; Tarvek enters the Castle with his cousin, Violetta, and joins Agatha's party. Upon learning that his father Klaus is preparing some of his special service units to destroy the Castle, Gilgamesh Wulfenbach, Schmott Guy also enters, accompanied by Zeetha, Krosp, Sleipnir, and Theo. After one important fragment of the Castle accepts Agatha as the new Heterodyne ("But theoretically, it's my huge mechanical death trap..." ) and launches an attack on the newly-arrived Castle Wulfenbach, Von Pinn descends from above .

The Castle is Fixed Edit


Here comes trouble..

Various other parts of the Castle remain uncontrolled and are still bent on killing everyone, finally forcing Agatha to shut the entire structure down using a modified version of Zola's Castle-killer. Following numerous Zola-induced delays, the Castle is resuscitated using a copy of its personality that had been previously downloaded into the body of Otilia, the Muse of Protection, as part of an experiment by Lucrezia. Agatha thwarts Tiktoffen's attempt to control the Castle, and the various protagonists go on to repair the remaining breakages in the Castle's systems and reconnect its central power source (an enormous water-wheel in the Dyne), allowing it begin contributing to the defense of Mechanicsburg against both the surrounding Wulfenbach forces and a swarm of opportunistic Sparks. (The surviving convicts are also freed from their sentences, as per agreement.) Agatha then tops all this off by giving the Castle a much-needed jolt, allowing it to truly unleash its power and activate numerous hidden security features put in place by the Old Heterodynes; as this process reemphasizes, it is not at all clear where the Castle ends and the town of Mechanicburg begins . All remaining hostile forces are driven from Mechanicsburg.

The Castle and the Time Freeze Edit

In response, Baron Wulfenbach personally launches a last-ditch attack with the Take-Five Bomb, a Black-level device which freezes all of Mechanicsburg (and himself) in a time-stasis bubble. For the barely-escaping Agatha and the reader, there follows a two-and-a-half year Timeskip. She/we learn that Gilgamesh, now running a much-reduced Wulfenbach empire, has surrounded Mechanicsburg with enormous walls and launched a massive scientific undertaking designed at "tunneling" into the frozen city. During one expedition into the city by Gil and Airman Higgs to extract test-subject Captain Vole, the Castle reveals it is able to resist the effects of the time-bubble, at least to the point of having a conversation with them. All three of them are unpleasantly surprised to learn that Klaus's activation of the Take Five bomb has attracted the unwanted attention of a massive and quite Hideous Extradimensional Being. The Castle calculates Agatha and her allies have two years to undo the time bubble before Something Very Bad Happens.

Bits and Pieces Edit

At some point following the Other's attack, at least one fragment of the Castle's distributed thinking engine with inert personality runtimes is smuggled out of Mechanicsburg and ends up in Paris, where it is acquired by Du Quay in his mad attempt to usurp the city's Master, Simon Voltaire. Soon after arriving in the city herself, Agatha is kidnapped by one of the Master's more loyal underlings, Drusus Beausoleil, in an effort to sabotage Du Quay's plot (and simultaneously assess Agatha's prowess as a Spark). By the time Agatha has been shown the fragment, a Telluric Wave Conductor has been attached to it and used to insinuate the Castle (at the time still in a low-functioning state) into every mechanical thinking engine in Paris. Agatha co-opts the Castle fragment, fully reactivating its personality, and it immediately recognizes her as a scion of the House and its mistress, through a vocal waveform analysis, despite (presumably) not being privy to the blood test proof carried out by the main Castle. After thoroughly destroying Du Quay's plot, Master Voltaire appears in person and disconnects it before it can truly do damage to the city.

Portable Castle Edit

Agatha is granted an audience with Voltaire and is tasked with extraction of all of Du Quay's hardware. After extracting the Castle fragment, she installs it into a Dingbot-like body shaped like a miniature fortress, with tiny organ pipes poking out the top. This "Portable Castle"[8] joins The Beast in its reduced state, and immediately proves its worth by hijacking Beausoliel's current clank body when he is not forthcoming with information that Agatha needs. It further shows it is able to remember other information from when it was "hooked into" Paris: namely, the location(s) of potentially useful mechanical devices.

The Portable Castle remains with Agatha as she travels to the Parisian Black Market and then to some of the apparently numerous secret underground kingdoms beneath Paris as well as the the Incorruptible Library, proving its worth by helping her track down Professor Zardeliv and unlock the Hermitorium of Master Spark Van Rijn.

Named locations within Castle Heterodyne Edit

Gates Edit

Corridors Edit

Rooms Edit

Other Edit

Monsters, Clanks, and Traps Edit

Devices Edit

Rules of Castle HeterodyneEdit

As thoughtfully compiled by untold numbers of prisoners at great hazard, and explained by surviving sources:

  • Duck under any doorway taller than one meter; these are also traps that will kill you. (Zola)
  • Don't touch any metal surface; it is also a trap that will kill you. (Zola)
    • Gold coins are metal too: Don't try to pick up ones spotted lying on the floor; they are pit traps. (Castle demonstration .)

Fan VideoEdit

Castle Heterodyne

Castle Heterodyne

Possibly relevant outside informationEdit

In its exterior appearance, Castle Heterodyne bears a certain resemblance to Castle Frankenstein as it appears in the Mel Brooks comedy film Young Frankenstein.

It also appears to be similar in appearance to Saint-Michel d'Aiguilhe (St. Michael of the Needle), a chapel on top of a volcanic plug in Aiguilhe, near Le Puy-en-Velay, France.


  1. The Kestle vould know.
  2. De Kestle vill keel dot vun.
  3. Carson prepares to speak for the Castle
  4. A 'Bridge of Trust' is built
  5. Carson relates his memories of the attack
  6. Carson relates further memories of the attack
  7. they've been working for... Wooster: fourteen years.
  8. It seems reasonable to use the name "Portable Castle" for the dingbotized Castle Heterodyne fragment because it seems quite appropriate and because this name was coined by Kaja Foglio herself! She wrote, "I love the portable Castle. <3 --Kaja," on the girlgeniuscomic LiveJournal blog entry for October 27, 2015.

See also forum discussion on Multiple AIs in the castle.

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