Chekhov's Gun: Those silver keys Jaden picks up from the fairies that waylay them? Turns out silver really screws with potions....
Cursed with Awesome: Bryant gets turned into a Beast Brood (human/lycanthrope hybrid) thanks to his blood mingling with Salla's after the accident, so he has to keep his new ears, fur, and tail hidden as part of The Masquerade, but hey, he's faster and can use Le Parkour. Salla also counts, since Thanatos' experiments were pretty horrific, but her fur's now fireproof and acidproof.
Dark-Skinned Blonde: Bryant/Jaden's Beast Brood form invokes this, especially since he inherited a lot of were form traits from his accidental blood donor.
Determinator: Jaden has become one by the end of the story. Salla's legs are broken, he's had the hell beat out of him, and they've both just barely survived the climactic battle, and he still is ready to fight when he thinks Team 18 is going to get in the way of their escape.
Early-Bird Cameo: This was intended as a side story to my main books, which I'm still in the process of writing. As such, my main characters get involved. I also throw in a cameo for an OC of a friend's who might or might not show up in the main continuity.
Mad Scientist: Thanatos. He wants to be invincible, and he's sure as hell not going to let some petty thing like morality get in his way.
The Men in Black: While their job description is the same, Team 18 is most emphatically made up of good guys.
Meaningful Name: Thanatos was named after the Greek god of death, which he's trying to cheat. When Bryant (who's name means "noble." It was actually accidental on my part) changes his name to Jaden Leandros, his selected last name is pidgin-Greek for "lion man." Even his hometown's name, Delphi, is an allusion to Greek Mythology. And yes, it's a real town.
Secret Identity: Bryant is forced to drop his name temporarily as a precaution. Can't let the psychotic Big Bad track his family down, can he?
Shout-Out: I'm a huge freaking geek, so I loaded on the shout-outs. Of note is that I practically included a character from another series - Jim Qwilleran, from The Cat Who... Series, now runs a local bookstore. There's also a series of shout outs to Greek Mythology (The Odyssey in particular), given that it's what we were studying when it was assigned.
Take That: To The Odyssey. Quoth the newly-christened Jaden: "It's better than calling myself Antinous."
Theme Naming: All of Thanatos' homunculi were going to be named after Castlevania characters, but I ran out of good ones. So I switched to Marvel and DC comics writers. Yes, Quesada gets killed brutally. Happy?
Too Dumb to Live: Yes, Thanatos, chug the potion you've spent so long on that looks like it's been messed with. See what'll happen. To be fair, he was already pretty mentally unstable, and just wanted to finally cheat Death.
Volcanic Veins: Happens to Thanatos after doing what's outlined in the above bullet. And it's not without side-effect.