These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Archive Binge: Probably one of the most notable in webcomic history. Originally a print comic, when Girl Genius first became a webcomic it had two archives; one consisting of pages from the print comics, one consisting of the new pages produced after the website went online. When the version for people who started reading it online caught up with the version for people who'd read the print comics an awful lot of people read the newer half of the combined archive, the equivalent of four and a half books worth of pages, in one sitting. The website server went down for a long time.
Complete Monster: Lucrezia/The Other qualifies for this trope on the basis of enslaving and slaughtering many thousands of innocent people, betraying the world's greatest heroes, and being the worst mother ever - killing her own son, using her own daughter for a Grand Theft Me, and then plotting to kill said daughter when that plan goes badly awry. She shows no remorse or sympathy for anyone other than herself, whether they are a victim, an innocent bystander, or one of her own loyal minions.
Largely averted, as the Fanservice comes primarily from Agatha and Zeetha (or Gil and Tarvek, depending on preference) while Bangladesh DuPree, a very attractive Comedic Sociopath, has yet to show so much as a bit of cleavage. This is most likely a reflection of Phil Foglio's philosophy on sexuality from his XXXenophile days, which placed an emphasis on fun and entertaining situations. That said, Lucrezia Mongfish-Heterodyne in any body is HOT (and, unlike Agatha, uses it shamelessly). Meanwhile, Klaus is in remarkably good shape for his age, and is frequently partially clothed in his appearances, although he's an Anti-Villain.
In a flashback to the past, Klaus and Lucrezia agree on this trope with each other. Unfortunately Lucrezia is Eviler than Thou, and doesn't need a partner in crime.
As befits the title, several strips offer incredibly obscure references. Examples include a flirtatious Jäger referring to a waitress as his little nokedli (it's a type of dumpling), and a scientist complaining about working with inferior coprolitic components (see Unusual Euphemism).
Up there with Gurren Lagann. Reaches critical mass around Volume 11.
The Castle Heterodyne arc just kept escalating further and further to the Big Finish. To put it in perspective, the immediately following sequence, despite involving time travel, a twisted future resulting from Agatha's absence, and Hunting the Most Dangerous Game, was a relative relief by comparison.
There's always been a fair bit of Les Yay between Agatha and Zeetha, but the one-off strip has some fans seeing Agatha/Kaja.
Like You Would Really Do It: Klaus Wulfenbach, apparently killed in a random attack on the hospital, and his body hasn't been identified. Nobody, least of all the characters, believes that he's dead.
Magnificent Bastard: Almost every major character has at least one dastardly brilliant scheme worthy of this status, but they all also succumb to periods of recklessness and insanity; no one is magnificent consistently.
Tiktoffen. Holy shit. He acted as a spy for pretty much every single major power in Europe. Managing exactly what information he fed to each one of them about Castle Heterodyne in order to manipulate them to further his own ends, i.e. freedom and controlling the castle for himself. Alas, he did not count on the Castle's Undying Loyalty to the Heterodyne family, and the greater utility of wrenches over knives for smashing things, like his Restraining Bolt gauntlet.
Mary Sue: One side effect of the Spark is that non-Spark characters tend to be mesmerized by those who have it. Another is that physics tends to give way when a Spark has his or her heart set on something. You could say that the webcomic is an examination of what a few Mary Sue characters turned loose in an ordinary world would do. (Hint: Think 'world war'.
Lampshaded, as part of the story. A character tells a flashback tale of the Heterodynes, and adds her own character. Her name? Mary.
Agatha has shades of this too. She's a brilliant, beautiful, long lost heir to a gigantic kingdom that everyone follows with little complaint, who is rarely seriously inconvenienced by a challenge, with two handsome, brilliant boyfriends who are also heirs to giant empires and are also unstoppable.
The main character sparks all have shades of it, super scientists that are pretty, can make anything and are adept combatants. The only way you can really tell that Othar Tryggvassen is supposed to be a boisterous bruiser who is far more combat oriented is that he yells more than the other sparks, does more face punching, and less inventing, but he's implied to be just as good at the science (even if he occasionally forgets what something is called).
Memetic Badass: Klaus Wulfenbach and Old Man Death have earned the status a few times over. And Axel "The Unstoppable" Higgs.
Zola must die, thanks to what she does after her power-up.
The Jägers, based on the third panel here, freely chose to join an army of Evil, and rejoice in that decision. Most of them are still sympathetic characters however, and they still have some pretty good standards. For instance, they are intensely loyal to the Heterodynes, and they absolutely detest Mind Control, as seen with their hate for the slaver wasps. See the strip above. Besides, it's implied that the Jaegers all started out as Boisterous Bruiser types, and if they worked for Ax-Crazy mad scientists... well, so did the people they were fighting, usually.
Lucrezia crosses it the moment she enters the story as an active character.
She crosses the line, stomps on it a few times, then bends it into a horseshoe and throws it at the head of someone she doesn't like.
Merlot was an unrepentant Jerk Ass about being thrown into Castle Heterodyne. He threw Agatha out and burned everything, including the cryptographers, related to her importance. And then he got mad at her about it, like he didn't directly cause it all.
Avoided, barely, by the end of the Tarvek and Zola fight. She was already down and Tarvek kept on going; if not for some last minute interference, he would have strangled her to death with his bare hands. Despite the numerous arguments in favor of him doing so — that she had killed many people already, that she had just tried to kill Agatha, that she could neither be let free nor safely taken into custody — quite a few members of the audience were nonetheless queasy at the sight of one of the 'good guys' strangling a semi-conscious woman to death. Gil's last-minute interference saved Tarvek from a(nother?) possible Base Breaker moment.
Klaus has apparently done to his own son what Lucretia did to Agatha and copied himself into him as a method of control.
Never Live It Down: Tarvek's... "adorning" of Lucrezia-controlled Agatha. Even Gil heard about it. He still does it in his head sometimes, so he has only himself to blame for it.
Stop Helping Me!: Gil has this reaction a few times towards folks - most notably here, where he's trying to stop folks from describing his romantic reasons for trying to help Agatha. Unfortunately for him, he's being shouted down by an enthusiastic crowd, two trained circus performers who are trying to rile up said crowd, and two friends who like to see him squirm.
Squick: Lucrezia’s behavior towards Tarvek in Sturmhalten is very disturbing. She deliberately stays half-dressed and keeps making obviously sexual remarks, while wearing the body of her own daughter. Once she realizes that he's uncomfortable with this, she purposely teases him. The whole thing is made even more disturbing by how Lucrezia keeps comparing him to his father (who was obsessively in love with her to the point he tried to download a copy of her mind into his own daughter) and to Klaus (her former lover). Oh, and apparently Lucrezia was the one, who designed Tarvek as her ideal Storm King candidate, possibly planning to marry him later in Agatha’s body.
Ugly Cute: The toothy, beady-eyed, eight-legged little revenant-detectors that were re-engineered from weasels.
Unfortunate Implications: In-Universe. Gil wants to keep Agatha safe and protect her from Klaus, and tells her so. It didn't occur to him that she might be offended by the implication that she, the Heterodyne heir, with the most impenetrable fortress in Europa, is a vulnerable damsel to be rescued. In fact, it's so stupid that Tarvek concludes Gil must be under mind control.
The Untwist: Supposedly the Baron died when the battles in Mechanicsburg started and the hospital got bombed. Very few were surprised when the Baron showed up, very much alive, some time later.
Martellus interrupts Gil—a Spark who is clearly in the madness place—while Gil's attempting to get answers about the fate of his girl, close friends, and his father, who've all been missing for two and a half years. Moreover, he interrupts Gil in order to taunt him that "with luck" said girl is beyond Gil's reach forever. It quite predictably earns him a brutal beat-down and Gil ordering his enforcer-clank that "If he says another word, cut off his head and pack it in snow."