AI Is A Crap Shoot: Victor Mancha, whom Ultron built to be an ultimate villain, and who rejects this role and stays on the side of good instead (not counting alternate timeline hijinks). Just par for the course for Ultron...
And Zoidberg: No one commented on this that this player remembers, but the people Karasu targeted were all close to Kurama (or one degree removed in Kaga's case) ...except Mikami, who just picked the wrong person to squib/lecture.
Arson, Murder, and Jaywalking: the Sue houses: one for sluts, one for bitches, and one for people that like sparkly things. (Qanonreip doesn't count in this instance as it's for applications that muns drop out on).
Ascended Fanboy: Victor Mancha, who was a huge superhero fan before realising he had super powers of his own. (Also subverted by him, in that he was programmed to be a fanboy so that [spoilers].)
Ascended Fanon: The term 'sparklepire' is now a canon term, thanks to George.
George St. Bartleigh has joined them: he's been turned into a sparklepire by accident. Although he's a subversion, he had a small Heroic BSOD about becoming one, then bounced back to his cheery if idiotic self.
Breaking the Fourth Wall: Very difficult to do in character, but happens often enough in the narration. Particularly with one player
Breath Weapon: Ancalagon and Smaug are the most obvious examples, being fire-breathing dragons. Níðhögg breathes a variety of extremely corrosive/flammable acid.
But Not Too Foreign: Ofdensen is half-American, three-eighths German, and one eighth Danish. Which is just enough Danish to piss off Skwisgaar, and probably enough German to be accused of being a Nazi.
Bullying a Dragon: Toki Wartooth is a perfect example, given his tendency to go homicidal and murder people with his bare hands (and head!) after they push him too far.
Fake Memories: Taken to the extreme when a 'sixteen-year-old' Victor Mancha found out he's actually a cyborg built just a few years ago, and that his entire life up till then was one big fabricated memory.
Instant Awesome, Just Add Dragons: Arguably all of HH's dragons (Smaug, Ancalagon, Níðhögg), as they tend to keep to themselves and out of the proverbial spotlight, but it's still awesome to have sentient dragons at Hogwarts. Lurking.
Ofdensen totally believes in this trope. He just won't admit it.
Involuntary Shapeshifting: Another possible outcome of a chocolate plot.
In the Blood: Miranda, who inherited a tail and, apparently show-business abilities from her real family.
Informed Ability: Usually done by the muns if there a canon ability that might come across as godmoddy if the other player isn't familiar with the canon.
Ryuk and Mikami can know a person's name and lifespan (if the person isn't already dead) just by looking at them, thanks to having shinigami eyes.
Austria and Sweden can tell a person's nationality just by looking at them (it's been likened to being like hair color for them, really obvious). It's currently unknown if Finland has the same ability.
Amaranth has a similar ability, except of knowing a person's nationality, she knows a person's sexual kinks.
Instrument of Murder: Skwisgaar is capable of literally killing people with his guitar in canon without damaging it at all; at Hogwarts, he unknowingly stopped Jasper from eating him by accidentally smacking the vampire with his guitar. (Virtually indestructible sparklepire vs. mysteriously waterproof, indestructible guitar? The guitar actually won.)
Jerkass: Lezard, Turlough, Alan Grant, Rat, Steff, Liandra, Bucky.
Kick the Dog: Both figuratively, any time A is targeted, and literally, when Wishbone is targeted.
Valentine's torturing of house elves.
Kid with the Leash: Alucard and Joachim, in a weird way. Became literal when the now sadly popcorned Ryuuji and Terry gave Alucard some kinky collar and leash gear to use on Joachim, who never quite understood their humour.
Les Yay: Does not happen that often, simply because there aren't as many females as there are males. But, Turlough (who had been turned into a catgirl) and Kuronue (who had just been genderswapped) did have a sex scene together as girls.
Nightmare Fetishist: Miranda Barker could be considered one of these considering her fascination with the warped, diseased, or dead human form.
Older Than They Look: All the countries, who despite being hundreds of years old (Austria is confirmed to be 1033) look no older than thirty.
All the Tolkien Elves (Elrond, Glorfindel, Legolas).
All the sparklepires (Jasper, Edward, Alice) except George, who only recently became a sparklepire (and remember, he came from World War I).
The Castlevania crew too: Joachim (vampire) and Alucard (dhampyr).
Most demons (Kusuriyuri, Kurama, Karasu, Kuronue.)
China Sorrows: been around for near a century, or so, but only looks mid-late twenties.
Rory is a borderline case-he has the memories of his Auton duplicate, who guarded the Pandorica for almost two thousand years, yet he is still flesh and bone. (This makes him mentally about twice as old as the Doctor, who obviously also falls under this trope...)
Susan Foreman not only falls under this trope herself as a Time Lady/Gallifreyan, but makes it much more apparent in the Doctor's case, as she continually refers to him as Grandfather.
Omniglot: Many of the Wammy detectives. Mello in particular; he learned more archaic languages and just adapted to whatever country he happens to be in. Averted with Matt, who only knows three languages, and one of them is fictional.
Ofdensen speaks German and English fluently, and has picked up some Swedish and Norwegian.
Kaga knows English, French and Japanese, though he usually only speaks Japanese.
In canon, Turlough could understand any language, thanks to the TARDIS. Whether this applies here is up for debate.
Liandra, thanks to hanging around humanity for their entire existence.
One Steve Limit: Played straight in that there cannot be multiple versions of the same character (ex: both the Kingdom Hearts and the Ansem Retort versions of Axel), but averted in that there can be multiple characters with the same name (there have been at least two different Deaths at the same time)
Our Dragons Are Different: Tolkien's Smaug subverted the Western Dragon trope by being intelligent, magical, and capable of speech, trendsetter that he is. Ancalagon is another example, though he'd sooner eat you than enjoy a good riddle-game with you.
Angels. There are those that have been humans, and there are those that have been around since the beginning of time.
Vampires. Some sparkle, some have bumpy faces.
Shoggies... Just... shoggies.
Dwarves. Oly was a genetically engineered freak.
Our Werewolves Are Different: Skwisgaar has been permanently afflicted with a condition that turns him into a merman every now and then, without the aid of hexed food or drink, making him something like a weremerman.
Papa Wolf: What Charles Ofdensen is to Dethklok (sans Nathan), generally without them even being aware of it. Although Skwisgaar has admitted that he pretty much considers Ofdensen the father he never had, much to his manager's confusion. (Skwisgaar was also kind of high at the time, and may deny saying it if ever asked about it, but he meant it.)
Perky Goth: Nemi. Sometimes. But she's definitely known for her Deadpan Snarkiness as well, so she is a mix between Perky Goth and The Daria. Sage, half the time.
Perspective Flip: Arguably, this happened every scene, due to two or more people playing two or more different characters in the same scene.
Rape as Drama: played straight many times, the notable ones being Beyond raping A (and makes an attempt on Matt) and Karasu raping Chairman Kaga
Rape Is Love: Near and Mello's first time happened under rather dubious circumstances. They are now one of the OT Ps of the RPG.
And now Nny/Teatime. As one of the muns put it "Consensual, but iffy".
Real Men Wear Pink: Sweden is actually more of a housewife then some of the women here. (He is quite fond of sewing)
Zex thinks his prefect's hat (a pink bow) makes him look quite the stud.
Real Person Fic: Technically against the rules to play someone who actually lived, unless it can be sufficiently proven that the canon's version of that person is different enough from the real life person. Example: Sanada Yukimura of Samurai Deeper Kyo, a more supernatural version of the real Sanada Yukimura, and Andrew Jackson of Ansem Retort, a very exaggerated Memetic Badass disembodied head version of the real Andrew Jackson.
Reality Warper: Amaterasu, courtesy of her being a deity and using her Celestial Brush.
Really 700 Years Old: Methos comes to mind as the most obvious example, but there are several others.
Austria, who is confirmed in canon to be over a millenium old. Presumably, Sweden as well, though they don't have confirmed birth years yet.
Elrond and Glorfindel, being over 6,000 years old (and Glorfindel possibly over 10,000) are prime candidates; Legolas has been presumed to be around a respectable 500-2,000 years old.
Vincent Valentine to a smaller extent.
Red Eyes, Take Warning: Mikami still has their shinigami eyes. Ancalagon and Smaug both have glowing red eyes, and looking directly into them results in dragon-spell mind control. Fun!
Kuronue, if he's really angry.
Somewhat subverted with Vincent Valentine, who has red eyes when himself, yellow when one of his demons take over.
Reptiles Are Abhorrent: Ancalagon and Smaug. The Jurassic Park raptor, who's shared some downright adorable interaction with Jasper and Toki, may be an exception.
Reset Button: As equally often as not, unpopping serves as this.
Ridiculously Human Robots: Victor Mancha, who looks and acts so much like a normal teenager that he himself didn't know he was a robot for years.
Shotgun Wedding: The Sorting Hat officiated over one when he mistakenly believed the bride was pregnant, then he went crazy and married off half the school. Recently, he forced Turlough and Hagrid to marry, mainly to see if they try to kill each other. (They have since divorced due to conflicting feelings on Turlough's part over the Doctor)
Subverted with Kusuriyuri and Kurama, who are both staff members.
Parodied (kinda) with Turlough/Hagrid, who were forced to marry each other. (Turlough used to stay with him because he isn't that bad a husband, and is more miffed about being forced into a marriage with an Earthling. They have since divorced over Turlough's conflicted feelings for the Doctor.)
Ofdensen/Nathan, though they got together long before Ofdensen took a professorship
Teen Genius: Every Teen Genius from Death Note has made at least one appearance. Even Amaranth would qualify, not that you'd notice.
The Ditz: Toki Wartooth, Beowulf, Sage. Amaranth has her moments.
Translation Convention: Canonically done by the magic of Hogwarts, done for the convenience of the players. Subverted a couple times, namely when two people speak a language a third doesn't, in the hopes that the third doesn't understand.
The group of people that banded together to stop Karasu, and now Apos.
Dethklok, in a really messed up way.
Truth Serum: Potion. Close enough. The alphabet detectives have experimented some with it, and Ofdensen slipped Toki truth-potion laced vodka to find out the truth about his and Skwisgaar's relationship. The Master also ate some truth-inducing chocolates while in the compy lab, causing him to troll the whole school, completely blowing his attempts at being incognito.