The Geisterdamen (en: Ghost Ladies) - also known as Weißdamen (en: White Ladies), Spider Riders, and Ghost Ladies - are an order of priestesses in the service of Lucrezia Mongfish, inasmuch as she is the manifestation of The Other.
A Mysterious Background
How precisely this state of affairs came to be is still unknown, although according to the Geister High Priestess Vrin, the seemingly-immortal Lucrezia has been their ruler for generations, reappearing in the Geister homeland at regular but lengthy intervals.
Where exactly that homeland is located is another of the very big questions. They refer to Europa as "the Shadow World" and were Holy Child," taken from them by person or persons unknown after Lucrezia left said child in their care. Led by Vrin, they made this trip through by a gateway device built by Lucrezia and then were by the gate's destruction by the rebel Geister Loremistress Milvistle. Milvistle also managed to destroy the plans for the Summoning Engine intended to be used to put Lucrezia's mind into Agatha's body, forcing Vrin and Aaronev Wilhelm Sturmvoraus to cobble together a barely-functioning replacement.by The Other to search for their goddess's "
As their names imply, the Geisterdamen are all female and ghost-white, with a number of similarly pale beasts presumably brought with them. The most iconic are their giant spiders, of course, but others have been spotted, including what one might term a "Geisterdragon" and large beasts used to haul carts. At least some Geisterdamen are themselves or qualify as, for testing purposes. It is implied that they normally do not cut their hair; Vrin does so as a mark of shame following Milvistle's actions.
As the story starts, they have been roaming Europa for (unsurprisingly) as long as Agatha as been alive, leading to a body of hostile folklore among the natives they have encountered: claims that they steal babies, cause revenants, blight crops, and all the other standard ills that get attributed to the strange and creepy — though we've learned that the service of their mistress, and their aforementioned search for the Holy Child, may account for at least the first two of those, as well as the general dearth of female sparks in Europa. (Again, see above about the non-functional Engine.)
They wear a white uniform consisting of a wrapped or lamina-style bodice with shoulder caps (no sleeves), and a loincloth; the High Priestess is apparently marked out only by a gold necklace. A Gilgamesh Wulfenbach from the Future has been seen wearing a similar outfit, as shown in the picture to the left, a fact apparently too strange even for much theorizing.
Among themselves, Geisterspeak". It is distinct from the common language of Europa and incomprehensible to run-of-the-mill Europans, although learned by the royal family of Sturmhalten ( , and by implication the late Prince). Othar Tryggvassen (Gentleman Adventurer) to communicate initially with Oslaka; eventually she taught him her language, whether he returned the favor is likely but currently unconfirmed. Lady Vrin is also fluent in Lingua europa, and later Eotain and Shurdlu are able to speak (evidently) French.that one might term "
Speaking of which, a large number of them manage to infiltrate Paris as part of a Slaver-wasping plot and attack Grandmother's grand soiree, resulting in most of the present cadre dying at the hands of Simon Voltaire, or during the subsequent mop-up operations. (Eotain may be the only survivor.)
According to Agatha H and the Clockwork Princess, all Geisterdamen we have seen so far have apparently been members of a contingent of The White Elite, three thousand strong. The novel also has Vrin give a slightly longer description to Agatha of the Geister's home and relationship with Lucrezia, though not to the point of answering any major questions.
In the prologue to Agatha H. and the Siege of Mechanicsburg, Lucrezia has a Geisterdame (note preferred singular) named Glimtoccka apparently acting as a bodyguard as she performs her scientific abominations. At another point in the novels it's noted that a dead Geister was found in Lucrezia's wrecked lab following the attack on Castle Heterodyne.
On his Twitter account, Othar details his adventures with Oslaka and later (by our perspective at least) a post-Paris Eotain, during which he drops some info about the group. He comments that to an experienced observer such as himself, they do look different than each other, and their personalities vary widely, as we have seen in person with the stoic amoral Vrin and more cheerful and outgoing Eotain and Shurdlu. They have very few personal possessions, but treasure small gifts that they pass back and forth between each other; Othar is careful to collect Eotain's when he takes her into "custody." At some point Oslaka tells him the Geister civilization is located underground.
Oslaka and Eotain both display fear at the sight of the moon. They also both, evidently, are not under slaver-wasp control, despite Vrin's being declared a revenant by a wasp-eater in Sturmhalten. Oslaka states she is not obligated to seek out her sisters and voluntarily goes off and lives with Othar as his common-law wife. Eotain, while displaying more hesitation, accompanies him to Holfung-Borzoi after he extracts her from Paris. She also appears to harbor bitterness over the paucity of information doled out to her while serving The Other.
The Girl Genius Complete List of Absolutely Everybody! states under the Lucrezia entry that their home is near the "secret base/summer home" of her father Lucifer Mongfish.