Dimitri Vapnoople, better known by Castle Wulfenbach residents as "Dr. Dim," was once a talented and domineering Spark who specialized in animal-based constructs, and had an extreme enthusiasm for "monsters." He a strain of giant wolfmen who were so powerful even Baron Klaus Wulfenbach couldn't corral them into his empire, and somehow unleashed the "Great Cetaceans" against Albia of England.
Vapnoople was nevertheless finally captured by Baron Wulfenbach some time before the start of the comic, taken on board Castle Wulfenbach and subjected to the Baron's brain coring experiments. (The fact that the Baron only conducted these experiments on particularly troublesome and intransigent Sparks again hints at Vapnoople's power and personality.) Following these experiments, he was still alive, but suffering from severely reduced mental prowess, and so was put to work as a janitor on the airship under the guise of a "failed Construct".
It is in this capacity that Agatha first Moloch Von Zinzer. Going with him to get a ladder from the storeroom where he lives, Agatha encounters the collection of stuffed bears he has made. Vapnoople's extreme worry at the Baron discovering his "last secret", his bears, she agrees not to tell anyone, and promises "They'll be okay, I promise".him, when he is summoned to the laboratory where she is "working" with
This conversation is witnessed by Vapnoople's last creation Krosp, who was constructed on board the Castle ( the brain coring began, but presumably well before Vapnoople was reduced to his current state) with the stated purpose of being "The King of All Cats". Cats proving by their basic nature to be useless as intelligence assets, Krosp was sentenced to be destroyed, but escaped and took up a covert residence on board the airship, watching over Vapnoople when he could. Following Agatha's act of kindness towards his creator, Krosp goes on to become one of Agatha's staunchest allies and flees with her from the airship.
Much, much later, it is revealed that Vapnoople was not talking just about the stuffed bears, but an entire army of living (and quite formidable) bear constructs which he somehow managed to create and conceal from the Baron, with the unknowing Krosp "coded" by scent to be as their leader. (Whether the whole "Cat King" thing was a hoped-for bonus or just a plausible cover-story is not clear.) Upon finally meeting Krosp in the Corbettite Depot Fortress of St. Szpac and officially control to him, the bear's stop-gap leader König further reveals that until now they have been taking orders from, or at least working with, Vapnoople's "number one apprentice": Martellus von Blitzengaard.
At this point, Krosp takes the bears and departs. He eventually Londinium, where it's revealed that they infiltrated Castle Wulfenbach, extracted Vapnoople and commandeered a Wulfenbach airship, with Krosp planning to meet with Queen Albia as a "fellow monarch" to request asylum for his creator. At first Albia is violently opposed to this idea, based on (at a minimum) Vapnoople's previous crimes towards the cetaceans, but upon seeing first-hand the man's current mental condition, relents and allows him to stay. Taken along with Agatha and Krosp to the undersea dome of the Queen's Society, Vapnoople receives a "covert" visit from fellow monster-enthusiast "Tobber" Homlomium, after the latter man's supposed demise. This turns out to be a ruse; he is actually visited by Trogulus, who is pretending to be Tobber in order to convince the "Gray Hood" conspiracy-members that Tobber is not yet dead.Agatha in
Hearing that there are monsters involved, Vapnoople follows everyone else down to the scene of Lord Snackleford's summoning of the extradimensional Red, in an ancient temple beneath the dome. He strikes up a conversation with "Karl Thotep", another extradimensional being, but has trouble expressing himself because of the damage the Baron has done to his brain. Karl is interested in hearing what Vapnoople is trying to say, and so lays his hand on Vapnoople's head and instantly the damage. Unfortunately, this restores not only Vapnoople's intelligence but also his evil (or insane, which comes to the same thing in practice) Social Darwinist desire to "improve" human society by having rampaging monsters kill all but the most strong and capable of our species. Vapnoople immediately begins battling with the newly-ascended uber-Spark Snacky, and summons the "true rulers" of the temple, a whole horde of extradimensional monsters. Agatha is able to banish them all back home; this impresses rather than angers Vapnoople, and he declares Agatha is his new apprentice. Plus he a distracted Snackleford and tosses him into the closing vortex.
He then has immediate second thought about this action. Not (of course) in any sort of remorse, but realizing he had just sent his opponent into a place of monsters and power. And so he decides to follow Snackleford into the closing vortex, and attempts to drag his new very unwilling "apprentice" along with him. At this treatment of his first and most loyal subject, Krosp finally rebels and bites Vapnoople. Mr. Thotep then interjects himself into the affair, pulling both Agatha and Krosp out of range. An enraged Vapnoopleto return as the vortex finally snaps shut, with him on the other side.
Later on, Tweedle reveals that before he became Vapnoople's apprentice, that role was filled by an England-based woman, the exact identity of whom he was never able to determine. And sure enough, not too long after that, we and the characters learn about a very likely candidate in the person of Francisia Monahan.
In the Novel
The novel Agatha H. and the Airship City features the ladder/stuffed bear scene as described above, but with Vapnoople displaying greater flashes of Sparkiness in regards to the type of ladder that is required.
Additionally, the novel has an second meeting between him, Agatha, Krosp and Theo DuMedd, set during Agatha and Krosp's escape from Castle Wulfenbach after the incident with the Hive Engine. Only now learning that "Dr. Dim" is/was Vapnoople, Theo offers some details about Vapnoople's history that the comic did not reveal until years later: he ruled over a large territory, controlled by the aforementioned wolf constructs who were powerful enough that it required a three-year campaign on the part of the Baron to subjugate them. Even after being defeated, unlike groups like the Jagerkin and the Lackya, these creatures could not be successfully integrated into the Wulfenbach empire and had to be entirely destroyed; it appears that Vapnoople made a point of ingraining deep loyalty to him into his creations.
Confirming this last fact, Krosp attempts to gather his "Papa" and take him along with them, but Dimitri refuses to come, referring to both his janitorial work and his bear army, which he adds was specifically created to wreck revenge on Klaus. When Krosp reluctantly leaves, Vapnoople rather casually says goodbye and promises to save Krosp a fish.
Dr. Dim is a card in The Works; the only epithet is Janitor. A player who "pops" (acquire for score) Dr. Dim is instructed to also pop the top card of the deck, which is, of course, unknown. (Not unlike Agatha acquiring Krosp, or Krosp acquiring the Swartzwalders.)