Theo's story at the beginning about the Dragon from Mars is a pure flight of imagination, but the Other's lab actually IS in the Heterodynes' basement and, if the novel's prologue adaption is accurate, the Other's base of operations is extra-terrestrial as well! Also, in this story Klaus got wasped. And soon enough...
Here the crowd calls Zeetha the Baron's daughter, which according to Word Of God is actually true — if the sketch of her father which looks exactly like Klaus is to be believed. Gil has also been called "the gol-dang Storm King" there, and some time later we learned of the Baron's plans to instate him as the Storm King.
Actually Pretty Funny: The Heterodyne stories frequently paint Klaus as a blithering idiot, but get away with it because he finds them hilarious.
The world is full of people with weird names like Gilgamesh, Moloch, and Theopholous living right alongside people with ordinary names like Bill, Barry, and Agatha; no one comments on it or seems to consider it odd. Nor is there any reason they should do so: in the real-life 18th century, you could find such names as Hieronymous and Cloudesley alongside John or Peter.
Moloch: 'S wrong with my name? My mother picked it out of the whachamacalit — the Bible. Repairman: Um— Did she read it? Moloch: Nah. I had eight brothers. Nobody had time for stuff like that on the farm. Repairman: Oh, yeah. That's pretty common.
A.I. Is a Crapshoot: Castle Heterodyne. Although it's arguably a subversion: since the guy who built it was an evil psychotic maniac, it's actually working pretty much exactly as designed. Agatha's own little "dingbots" are a straighter case, since they've sometimes stopped listening to her. Judging from the background events, it seems a frequent problem that Sparks can't build anything without it going haywire.
Allohistorical Allusion: As you'd expect from a universe in which electronics moved quickly enough for Rembrandt to be a roboticist, Galvani's eponym comes not from the effect of electrical impulses on muscles, but something involving molten zinc and Life Energy... which is often used metaphorically to mean electrical stimulation of muscles. Actually a Genius Bonus, as in real life metallurgy, Galvanizing refers to the process by which zinc (or another metal) is plated onto iron or steel to prevent rusting.
Alternate History: Perhaps better called Parallel History, because the Sparks have been around for long enough that even geography has been changed by their influence, and yet the world and its history are not completely dissimilar to ours:
There were still Mongol Hordes on cue, German is still spoken as a European lingua-franca, R(embrandt) Van Rijn was still a famous genius and Casanova a famous skirt-chaser, the [Weather] King was still a towering historical figure.
Additionally, the Storm King was called Andronicus Valois, and his being a contemporary of this world's Rembrandt means he probably really was the GG universe's answer to our Sun King (Louis XIV). This means the Valois line was still around and in charge fifty years after power had passed to the Bourbons in our world.
There is still a powerful church with not one, but sevenpopes, and, judging by a brief mention each with their own faction, apparently. note For those not in the know, there were several points in the church's history where either they went through a pope about every couple months to around 5 years, and another where there were 3 popes at once. Either or both could be the case for Girl Genius.
Always a Bigger Fish: The Jägers have, throughout the comic, been implied to be the most Badass Supersoldiers to have been cooked up by any Spark in Europa. But it turns out Klaus Wulfenbach has a Supersoldier race of his own called the Dreen; the sight of just one of these makes a Jägergeneral panic and desperately carry Agatha to safety, proclaiming "Doze tings iz unschtoppable! Vorse — dey's scary!"
Anyone infected with Hogfarb's Resplendent Immolation or Vericus Pantiliax's Chromatic Death, although as the names of those ailments may suggest, the affected person didn't start out that way and won't be that way long before something bad happens. Fans are now calling the sequenceending here the Amazing Technicolor Dreamboat Sequence. Yowza! Or Eeyyooww-ZAP!
Jägermonsters, and many other kinds of constructs. Mamma Gkika's skin color changes naturally, though she has some control over it and has stuck with a humanlike pink for a while in order to blend in all schneaky-like.
Bangladesh DuPree's pirate crew seems to be entirely female.
Geisterdamen (spider-riding, at that). Zeetha's mysterious tribe. Lots of Amazons.
Same goes for Heliolux Airship Fleet's flagship crew. Which is a communication and traffic control unit, so not directly involved in combat, although the white-red uniformed Commander remarks that they'll miss the fighting. On the next page she shouts to the entering Jäger that they're non-combatants. It's pointed out that although the Heliolux ships are mainly used for long-range communication, at close range the high-intensity light beams they use can also melt people and buildings.
The Devil Dolls, a foot soldier unit in the Wulfenbach army that are comprised of what is likely a series of female constructs of some sort that look somewhat like female tin soldiers, and were likely absorbed from the force remnants of some other spark that the Baron defeated. They're seen running from a monstrosity that came out of the ground when Castle Heterodyne really lets loose. They were likely a competent force against the general foes the Empire faced, but seriously... TheCastle.
And Now You Must Marry Me: It was suggested that Agatha's grandmother married one of the old Heterodynes, to protect her family from harm. It apparently later backfired, when she taught her sons, Bill and Barry, how to use their Sparky powers for good rather than evil, and in the end poisoned her husband.
Arbitrary Skepticism: In a world filled with lightning guns, mind controlling bug robots, and other insane science, Tarvek utterly refuses to believe Gil's flying machine can stay aloft without a gas bag.
When Othar and Sanaa are wandering the Castle, and she thinks things are all right.
Othar: We're in Castle Heterodyne with exploding collars around our necks, caught between a fake Heterodyne and a real one (as well as assorted criminals, maniacs, and various monsters), and I suspect that even if we found any beer in here, it would be evil, or at least flat.
Also involving Othar: "De dirigible iz in flames, everyboddyz dead an' I've lost myhat." To be fair, hats are a big deal to the Jägers whereas arson and murder are hobbies.
Professor Tiktoffen: Franz here liked turning people into beetles. Zonia believed that orphan blood had medicinal properties. Krag put his feet on my bed.
A villain learns why you must never punch a lady, or wake her up too early in the morning.
Now why would anyone want to kill Klaus Wulfenbach? Let's see...:
Gil:Why? Because Wulfenbach troops turned her village into owls. Or maybe we deposed her favorite mad prince, or hung her lover for piracy, or banished the Heterodyne Boys, or poisoned the well, or raised the price of herring.
The earlier strips have bizarre anatomy issues and ugly gradient coloring. (Also after the first volume there was a great deal of uneven inking.) These problems eventually disappear.
Volume 1 was originally published in black-and-white. Volume 2 saw the introduction of color, in searing neon gradient fills. The coloring eventually settled down and volume 1 was eventually recolored in a somber desaturated palette. The result cleverly mirrored Agatha's psyche, as her perceptions are dulled in volume 1, overloaded in volume 2, and by volume 4 settle into a happy medium.
Boris earns the respect of the Jägergenerals by beating their location out of a messenger.
Astonishingly Appropriate Interruption: During the play in Sturmhalten, just as Tarvek is saying "If the mistress were here, she'd say—", he's interrupted by Agatha (in-character as Lucrezia) yelling "KNEEL, 'YOU MISERABLE MINION!''"
Phil Foglio is well-known (unabashedly so) for drawing his female characters with rather large "assets". But it's his wife (and co-author) who loves to get Agatha into the "lacy underthings". She's a big fan of Victorian-era undergarments.
Phil admits the only reason the Jägers became recurring characters is because he really likes drawing them.
Author Avatar: The creators, Phil and Kaja, are both apparently natives of the story's world who, it would seem, will eventually meet, marry, publish a... controversial account of Agatha's deeds, and flee into our world with it to continue it safe from Agatha as a supposedly fictional comic.
The love/hate relationship between Gil, Agatha, and Tarvek runs so deep that a list of specific examples would probably end up getting its own page. Klaus and Gil, as well: when Klaus sends a small army to take him prisoner as all hell's about to break loose in Mechanicsburg, Gil's reaction is "he does care!"
Tarvek, who has maintained for years that he really really hates his childhood friend and rival Gil (who is mind-controlled after he is captured by the Baron), had an adorable one.
Heterodynes are a family of powerful Sparks with a signature hereditary ability of "heterodyning" or humming a specific way to completely tune out all distraction, who were feared and hated even among others of their own kind, to say nothing about the rest of the continent. They created Castle Heterodyne – an omnipotent sentient Supervillain Lair with a dark sense of humor and Jägermonsters – scientifically modified Super Soldiers, completely loyal to the house Heterodyne. Then Bill and Barry happened. They redeemed their family’s name by travelling across Europa and defeating monsters and evil Sparks, and were considered the greatest heroes of their generation. There is also the latest scion, Agatha – a powerful Spark in her own right who is just beginning to make her indelible mark on the world.
Klaus and Gilgamesh Wulfenbach. Klaus returned to Europa only with his infant son in tow and still managed to conquer a good chunk of the continent by himself, apparently for its own good. He is single-handedly keeping peace in his Empire by keeping rampaging madboys and arrogant nobles in check. He and Gilgamesh are both powerful Sparks and very potent fighters, to the point Jägers are scared of them. If rumors are true then there is also Baron's long lostBadass Normal daughter - princess Zeetha.
Valois/Sturmvoraus/von Blitzengaard family. Their ancestor was one of the greatest kings of all time - Andronicus Valois. Currently family consists mainly of Manipulative Bastards, backstabbers and McNinjas. Most prominent members are Tarvek - once again a powerful Spark, exellent shamer and a good fighter and Violetta - a Smoke Knight and an Impossible Thief.
Bag of Kidnapping: Sanaa and Othar do this to Tarvek, mistaking him for Gilgamesh Wulfenbach.
Bar Brawl: Apparently there's one every evening in Mamma Gkika's. Except on Thursdays; that's poetry slam night.
Bash Brothers: Da Boyz and the Jägergenerals. Klaus and the generals were having fun at some points of the wasp attack. The Heterodyne Boys were a more literal example.
Battle Butler: Ardsley Wooster and Boris Dolokhov, though, technically speaking, neither is an actual butler. Wooster is a spy posing as a valet or gentleman's gentleman; Dolokhov is more of an aide-de-camp, librarian, accountant, and general manager.
Battle Couple: To an extent, Agatha and Gil during the wasp outbreak on Castle Wulfenbach. When she, Gil, and Tarvek were battling with and through Castle Heterodyne, they were a Battle Threesome.
Agatha. She really is a very nice, pleasant, easy-going girl. Until she goes to The Madness Place or you hurt or threaten one of her friends. Then the Death Ray comes out.
Gilgamesh is usually rather pleasant and doesn't scream and beat people to get his way. Piss him off. Go on. Gilgamesh managed to scare the crap out of a Jäger (one completely off the deep end even for Jäger standards) and the resident version of James Bond.
Tarvek is the blue to Gil's red. He's rather charming and civil by default. When he gets mad, Zola up and surrenders. He doesn't let it end there. Oh, no. Instead, he's fully prepared to murder her with his bare hands.
And let's not forget The Indestructible Airman Higgs. Quite polite and decent, not to mention extremely low key, until he has to beat senseless everything within reach, while still probably not breaking a sweat.
Agatha's Death Rays. Played with, when she made a "very small" death ray. That she used to blow a hole out of the castle, taking out a chunk of a nearby mountain. And a hole from fairly high in the castle, to the basement. What a magnificent death ray!
"Si vales valeo" is Latin for "If you are well, I am well", a phrase used in ancient Roman times to start writing a letter like "Dear Mister Smith". In the world of Girl Genius, it has a more literal meaning.
The contraption Agatha is building here is named "Şoarece"; this is Romanian for "mouse" (not "the mouse", that would be "şoarecele") which is, in the same time, a bilingual bonus, and a genius bonus: Mechanicsburg is in-story located in Transylvania, and the real-life Transylvania is today part of Romania.
Black and Gray Morality: Agatha and Klaus are both sympathetically gray and fighting for perfectly reasonable reasons. There are several villains that are clearly black, and both of them want those destroyed.
Bleached Underpants: A variant, in that prior to Girl Genius, Phil Foglio was the author and artist of the XXXenophile series of pornographic comics, and unlike many artists with a similar background makes no attempt to hide it. However, before XXXenophile, he was already well known for What's New? with Phil and Dixie for Dragon Magazine, and Buck Godot: Zap Gun for Hire, and did book covers and illustrations (most memorably, for Robert Asprin's Myth Adventures series), as well as the classic Con Reports and a trio of excellent, funny updates of old '60s humor comics for DC Comics at about the same time as XXXenophile.
A lot of Girl Genius is made up of brilliant little ideas that Foglio previously used in his pornographic work. The Jägers' speech pattern and dental work? From XXXenophile: "A Beautiful Tail" and "My Favorite Oitling". Zeetha's jewelry, with the little faces that mimic whatever her current facial expression is? From XXXenophile: "Blue Opal".
The Spark itself. If you have it, you can warp the laws of physics with the contents of the average Store Cupboard. Bad part? You go insane to varying degrees whenever you do it. The natural result of that is that most Sparks, and Agatha in particular, have to deal with being shunned, used, or attacked by most everyone they meet. And that's if they don't get killed by one of their own creations. Or get the Torches and Pitchforks treatment.
Agatha before her breakthrough, when she wore the locket to suppress her Spark. It undoubtedly saved her life, but it also made her completely incompetent and destroyed her self-esteem.
Bling of War: Most troops are trying to look cool — some, too hard. Jägers tend to dress in less unified fancy clothes, with their own peculiar taste. Of "Da Boyz", Maxim wears the most fashionable set — he's an ex-cavalry officer, after all.
Blue Blood: The Nobility is one of the biggest opponents to the Baron. House Wulfenbach is of nobility, but low ranking. As such, the Blue Bloods see him as an upstart and a tyrant who has illegitimately seized most of their power. The Knights of Jove try to use the legend of the Storm King to reclaim it. The most notable Blue Blood characters are Zulenna and Tarvek.
Boring, but Practical: Moloch is easily one of the most rational people there, being a Only Sane Man of course, and a bit of The Engineer, his ideas are typically very unflashy, but they get the job done. Much to the ire of the sparks and mad scientists that surround him.
Snaug: ... spiky trap-doors... torture chambers... man-eating bats... impertinent mechanical squid... Mittelmind: Oh, there is some psychological damage, but I always wipe her memory for her birthday. Snaug: Happy birthday to meeeeeee...
A long time after Agatha is convinced that her battle merry-go-round is too dangerous to construct, a soldier who failed to capture her is diagnosed with a concussion for explaining that her injuries were sustained while destroying a merry-go-round.
Agatha: It could be a really evil town...
In the Cinderella special, the "evil step-mother" comments that Agatha could win the kingdom with a dead rat and a houseplant. At the end, she bribes the king, a cat, with a dead rat and potted catnip.
Gil throws Othar out of an airship, and when Agatha gets mad, he assures her that once she gets to know Othar, she'll do the same. An hour later, she does, and mentions, "I owe Gil an apology." About ten chapters later, she gives it to him.
Agatha: I got so mad at you, and then, within the hour, I threw him out an airship too! Gil: And you felt bad for throwing— Agatha: I felt bad for yelling at you!
The muses, the delicate creations of the greatest spark of the time. Most of them are destroyed or damaged while sparks tried to reverse engineer them. Known examples are Tinka, studied by Tarvek, and Otilia, found beneath Castle Heterodyne. She manages to cause some trouble in her "broken" state though.
Also Castle Heterodyne, damaged in the Other's attack.
Also, the circumstances of Gil and Agatha seem to be similar: he showed up and got disapproval for killing Dr. Beetle, even though "He threw a BOMB at me!", and then Agatha made the impersonator break down into tears, even though she'd tried to usurp her.
Calling Your Attacks: Done by Zola under the influence of a massive overdose of battle stimulants, resulting in a cry of "Chophead Tinybits!"
Came Back Wrong: Subverted. Apparently being brought Back from the Dead causes memory loss (as we have been repeatedly told) and frequently drives the recipient Ax-Crazy. However, when it happens to Tarvek, all it takes to bring him out of a homicidal rage is the following:
When Gil supports both Agatha and Tarvek when they get infected by Hogfarb's Immolation.
Tweedle pretty much calls the trope by its name when he explains how he hopes to make Agatha compliant by linking her metabolism to his, so that she can't leave his side and can't kill him. Unfortunately for him, he dreadfully underestimated the Heterodyne girl; soon enough, she had transfered the dependancy to a wasp weasel pet.
The Cat Came Back: Othar. He's very hard to shake off, especially when he has set his eyes on a "spunky sidekick". Throw him in a pit, he'll walk back through another door a few seconds later. Lampshaded by Tarvek after he and Violetta tries to escape him with a "down and up" (that doesn't work):
Tarvek:This is why he's a hero. He's very good at this.
Othar Tryggvassen: What, tyrant? Does your empire give you no pleasure? Klaus Wulfenbach: No. It gives me no pleasure. Politics always annoyed me. Now I do it every day. I haven't seen my wife in years. My old friends are gone. I haven't traveled or explored. At least with the Heterodynes we had the adventures. The occasional fight. Now it's send in the armies, then the bureaucrats with mops. It's become an old formula.
Master Payne: For all we know, those things are some new kind of revenant — and the only thing to do is kill them. Could you burn down people — women and children — even if you knew they had become monsters? ...The Baron can. The Baron has. I respect him for that, but I don't want to be him. No sane man would.
Chaste Hero: Barry Heterodyne, quite possibly. Barry always ends up with "the High Priestess" in the stories and plays, "The High Priestess" being the catch-all term for whatever lost priestess, Distressed Damsel, or mad scientist's beautiful but misguided assistant (other than Lucrezia) happened to figure in any given Heterodyne play (basically, an in-world trope). There is no indication Barry had a love life in Real Life, though. Also Agatha, thus far.
Then there's the poison pellet Gilgamesh gave Von Zinzer to use as a suicide pill if he chose. While Von Zinzer has shown up again (alive), the poison hasn't shown up again... yet.
Agatha's locket. It is introduced at the very beginning, then disappears from the story within the first few chapters. Then its importance is revealed — and then it comes back a second time, important in a brand new way.
The unearthly powers of the spring from which the River Dyne flows. The Castle gives exposition about how the first Heterodyne found it as a shrine to a local battle goddess, and how it would usually kill any who bathed in it but occasionally granted immense curative powers. Not being one for superstition, the first Heterodyne did the unthinkable: he drank the water. Sure enough, in the course of curing the case of Hogfarb's Resplendent Immolation, Agatha ends up drinking Dyne water herself, finishing the revivification and also proving to the Castle (again) that she is one of the family. And then after exclaiming that she's got to try that again, the Castle is doubly assured.
Perhaps the biggest Chekhov's Gun might better be described as a Chekov's Bullet Holes — we've seen a window into the future open three timesso far, but it is the cause of the effect that is as yet unknown.
Chekhov's Supersoldier: A pair of Dreen can be seen in an early double-page fighting slaver wasps during the free-for-all fight on Castle Wulfenbach. The creature, and its scary reputation, is formally introduced way later.
Chekov's Soldiers?: According to the weird future portal events that Bang saw, von Zinzer's "Bruno and the kid" are somehow important enough to use a bizarre past-viewing device to find out what happened to them after Bang blew the gunboat. No hint of their existence, let alone significance, has cropped up...yet. (Then again, Moloch hasn't admitted he's working for Agatha, Gil isn't wearing geister armor, they aren't working with any Geisterdamen, and Agatha definitely doesn't have wings on her trilobite, either.)
Chekhov's Skill: Agatha's training under Zeetha. Mind you, it's not like it was ever a secret it would be useful.
Chronoscope: The strange "windows" that appear at several points in the comic, with doubles of some of the comic's characters standing on the other side and observing events through them, may well be a case of a chronoscope seen operating from "the other side" — i.e. from the perspective of the observed, rather than the observing. Presumably, the device itself will show up and be used at some point in the comic, but that time hasn't been reached yet.
She later meets the curate, and apparently no one's seen a bishop in years. The cathedral seems to be run by an "abbess", who appears to basically be a bishop, on a medieval model — she has her own war-horse and everything.
Mechanicsburg — The town sport is repelling invasions. It's famous for being impenetrable, basically an entire town of Switzerland: heavily armed, booby-trapped, and anyone can be a combatant. But that was twenty years ago...
Pretty much every city in Europe, apparently, to a greater or lesser extent — a town is a place that protects you from the big bad world. It has walls. If it did not have walls, it would presumably be only a village. Paris, Beetleburg, and Sturmhalten are the only actual datapoints here, although Van Zinzer implies that anywhere outside the important towns can be pretty nasty.
City of Weirdos: Mechanicsburg. Lampshaded when one of the inhabitants wonders if growing up there made them weird. After he insures the town's children are safely in the protection of their ancestors... a group of undead crypt-dwellers.
Of course, the Jäger Funetik Aksent clouded this foreshadowing a bit by the line actually being "ze kestle is mad, dyink, useless." Since we didn't at that point have any reason to suspect sentient architecture, "ze kestle vould know" sounds like it's introducing a person called a kestle — a seer or something.
Old Man Death has a mini-flashback of people who rode with the Jägers — like the Seneschal. Still not sure if he's in there, though.
Crapsaccharine World: Actual science is basically dead, which has effectively halted theoretical study, which means that the development of atomic energy, computers, and decent aircraft is not going to happen. Why bother working on fruitless theories that might become something much later when you can have awesome stuff now? Societal progress has (except for a few things such as the role of women and racism) also basically halted, with most of Europe frozen in the Victorian era. Democracy is unheard of, and the Spark nobility often rule with an iron fist. The distribution of wealth is still largely at the top, with no sort of working-class consumer society developing. Oh, and there are monsters, diseases and devices that will kill you. This is, of course, covered up with a coating of awesome steampunk machines, a noble, chivalric attitude, and cheerful plays and books. The people seem mostly content. On the plus side, you can get Back from the Dead, have your life extended and there are heroes about.
The world is dominated by people and things who'd fit right in with Warhammer 40,000 Orks, and the only thing keeping them mostly in check is anti-villain dictator Klaus, who is quite willing to level cities in order to achieve such. His territory is described as containing a lot of empty space despite being central Europe, is littered with forgotten but highly-lethal Spark inventions, and walled-in cities are the closest one comes to safe. The Other systematically leveled much of Europe not long before that, and currently has free reign of Sturmhalten, a large army, and has mind-controlled Klaus. Outside Europe, things aren't much better, with northern nations having a tax on fire. The greatest folk heroes are missing, and the second greatest folk hero is a serial killer.
Rudolf Selnikov: The depressing thing? Twisted and ruthless as you people are, throwing in with you is a step up.
Alternatively, A World Half Full. Europa has mostly recovered from a devastating genocidal war that employed mad science bioweapons just decades ago, and is ruled by an extremely intelligent benevolent dictator who keeps the peace and lets most people get on with their lives. There are systems in place to contain the mad monstrosities that arise, and the people Othar has killed (usually) had it coming.
Crazy Enough to Work: You get the impression this happens a lot. Perhaps the most hilarious one would be curing Tarvek of a terrifying disease by killing him and then bringing him back to life. Even more hilarious given the way Agatha said the trope name. "This has a small, but fascinating, chance of actually working! Let's do it!"
Crime of Self-Defense: A short-lived running gag about Gil defending his killing Dr. Beetle with "He threw a bomb at me!"
Crippling Overspecialization: The elite Vespiary squad are deadly against some of the most dangerous monsters in the series. Other people tend to view them as no threat, correctly. Their intended purpose is protecting humans from wasps, bringing them close to Technical Pacifists when it comes to fighting humans.
Da Boyz. Oggie is the least bright of the three, but don't let that fool you.
Zola looks like a vapid fool, but then she drops the "vapid fool" mask and soundly beats Zeetha and Violetta, and matches Higgs — three of the seven most capable physical fighters in the main cast. (The other four are Da Boyz — Oggie, Dimo and Maxim; and VonPinn, who's a construct.) Though her physical abilities were boosted by a Deadly Upgrade, she did have to steal the upgrade — from a Smoke Knight — requiring a different kind of badassery.)
Castle Heterodyne. To the point where once it finds out that Othar Tryggvassen is a hero, it immediately dumps him down a bottomless pit. Of course, the castle knows all about heroes...
Castle Heterodyne: Oh tosh, if he was a real hero— Othar Tryggvassen: (comes through the door dusting himself off) This is an annoying place, isn't it?
Gilgamesh Wulfenbach seems to have taken a line from the castle. To ensure that Tarvek makes it out of Castle Wulfenbach safely, he handcuffs Tarvek to Othar, shoves them both in a broken flying machine, and drops it out a window.
Gilgamesh:He's always falling out of airships and stuff — so if you're with him — I know you'll get away! (drops them) Oh, and LET ME KNOW HOW HE DOES IT!
The Castle Heterodyne arc is an inversion of this, since a new hypotenuse came into play and a major chunk of a story arc was spent preventing his death.
And one of the "what if" stories even lampshaded this topic in amusing fashion. Why two love interests? (Giant grins from two female cast members and female co-author.) "Deal with it."
Death Ray: Just about every Spark has made one or something like one — though no-one but Agatha redesigns the landscape with them during sleep. Agatha considers Gil's NOT having built a death ray gross negligence of the highest order, going so far as to say "what's wrong with him?" He takes this criticism to heart, and most of his later inventions are somewhere between "Mobile Heavy Artillery" and "Force of Nature".
Deliberately Monochrome: Volume 1, "The Beetleburg Clank", makes wonderful use of this. Before Agatha's locket is removed, the comic is almost entirely in grayscale; the only color is some blue around the sound effects of Sparks' machines (and Agatha's Green Eyes). Right after the locket is removed, the colors are present but dim, as her Spark starts to assert itself although she still gets headaches — but in her most Spark-ish moments, the colors are bright and clear. By Volume 2, when the headaches have stopped, the entire comic is in full color. One flashback in Volume 2 shows the color fading the moment Agatha puts her locket back on. Originally, the first volume was black and white (it was a print comic) and that was the end of it. The retconned color is just full of symbolism.
Deus Exit Machina: Castle Heterodyne is able to instantly crush anyone in a "live" room, with extraordinary precision. Naturally, all the action takes place in rooms where the Castle isn't yet repaired, so it can't help out.
Didn't See That Coming: Happens all the time. Just when the characters think their plans are set, just when the audience thinks it knows what is going to happen next, some Chekhov's Gun will be taken off the mantle and fired, some character who we haven't seen for several months or years will suddenly reappear to immensely consequential effect, or some machine will malfunction at exactly the wrong (or right) time, radically reorienting the direction of the plot in a very short amount of time.
Dirty Business: Barry, in the flashback where he gave Agatha her locket, is crying over the effect it will have on her.
Less jerk and more questionable bedside manner. Agatha to Tarvek.
Dr. Sun also has that reputation.
Selnikov: Ah, yes. That "Sun-ny bedside manner" everybody talks about.
The Dreaded: It's strongly suggested that the old Heterodynes were this to the whole continent. Even after Bill and Barry redeemed their family's name and there was no Heterodyne in residence, people of Europa felt much safer with Mechanicsburg completely disarmed.
Enfant Terrible: Not quite yet, but when Gil rides out with the "devil dogs" to defend Castle Heterodyne until it's all the way fixed and goes into full-on ape-shit Spark mode, this conversation happens:
Council Member: But—I thought the new Heterodyne was a girl! Vanamonde: She is. That's just the boyfriend. Council Member:That's— Vanamonde: Uh-huh. Council Member: We're...we're going to have to break out those little iron cages for their children, aren't we?
Even Evil Has Standards: Averted in the radio dramas: Othar's query to a pirate captain of "Isn't that a bit sexist?" is responded to by saying that they're evil, they're basically politically incorrect for a living!
Everyone Can See It: Mostly played straight, in that anyone who meets either Gil or Agatha and merely hears them talk about the other knows they're madly in love, but they know it too — they just refuse to admit it (though Zeetha finally got a confession out of Gil).
Evil Albino: The Geisterdamen, an order of ghostly-white priestesses who are in the service of the Other.
Evil Gloating: Sparks in general, and particularly evil ones, seem to be fond of doing this.
Evil-detectingWeasel: The "Wasp eaters", an engineered construct species designed to detect and sometimes kill Slaver Wasps. Were nearly useless before, since slaver wasped people turned into rather conspicuous mindless Revenants, but recent advancements in the Slaver Wasp technology led to sleeper agents, which the wasp eaters are quite useful in detecting.
Pages of Girl Genius are named in groups. Examples of these titles include "Gil deals with it", "Monster Horse Beastie" and "Barfight, also Higgs" (the latter reintroducing Airman Higgs in the middle of a bar fight).