Action Girl: Several, mostly Careers, but Demetra is probably in the running for most triumphant example.
Kali would like to contest that assertion, though she is more of a Dark Action Girl herself.
Action Survivor: Lectic, definitely. He is alive thanks to a generous amount of intervention on Demetra's part, and a good amount of luck and intelligence on his own.
See also Carden, Hypatia, Holland, Actassi... most of the non-Careers who actually... y'know, survived. The bloodbath, anyway.
Action Duo: Lectic and Demetra do pretty well for themselves, though Demetra would sooner cut her tongue out than admit it.
Aerith and Bob: Rachel/Asha/Tanner/Diane: all relatively typical names. Auroch/Hetcher/Rippel/Pasque: not so much.
And Now For Something Completely Different: Enforced. Fanfiction.net doesn't allow list-format stories, so the first page of With A Capitol G (a character list) has been replaced with a place-holding Crack Fic while the story is on hold.
Anti-Hero: Soren, Lucian, Demetra... a good portion of the Careers.
Comically Missing the Point: Demetra's friends spend most of her interview time gushing over how lucky she is to be in the Hunger Games with a cute guy and a flamethrower.
Curb-Stomp Battle: Subverted. Strong, smart Auroch is beaten by not one, but two of his Games' youngest contestants. You gotta feel sorry for the poor guy.
Also, the cave on the island with the freshwater spring that Hetcher, Diane, and Carden always seem to find their way back to.
Incredibly Lame Pun: The author has a sort of love affair with these. A Capitol Experience? A 'capital' experience! Capitol Punishment? 'Capital' punishment. With a Capitol G? With a 'capital' G.
In-universe, Demetra makes a comment to herself about "pushing [the] buttons" of a girl wearing a calculator costume.
I Was Beaten By A Girl: Soren and Kali had an similar dynamic until she killed him and cut off his jaw.
Just Friends: Lectic and Demetra. Hetcher and Diane. Diele and Dylan. Maren and Actassi. The Capitol Series is rife with this trope.
Kill It with Fire: Demetra's general attitude towards anything that bugs her. The flamethrower helps.
Lack of Empathy: Lucian. Word Of God states that he was borderline autistic before suffering a skull fracture, and picked up a few worse traits accompanying his not-quite-recovery and the encouragement of District Two's warped values.
Kali from aCE was a perfect example of The Sociopath, no genetic disorders involved aside from whatever is going through most District Two DNA.
Out, Damned Spot!: After Sherman's fever-induced hallucination leads him to believe he murdered Twyla, he tries to wash the black blood off his hands, to no avail.
Playful Hacker: Lectic is somewhere between this and The Cracker. He has no real malicious intent, but he does use his hacking skills for material and monetary gain.
Quit Your Whining: Demetra really, really doesn't care about other peoples' problems. Especially when they're getting between her and a giant vulture. Even if it's Lectic.
Sacrificial Lion: Quite a few of them. A Career or two tends to kick it in the bloodbath, too, adding the less-sympathetic variety.
Salt and Pepper: Word Of God confirms that Lectic is black and Demetra is white. They couldn't be more different. Their races, however, are rarely even alluded to, and definitely not a plot point.
Lissom's inner monologue has a tendency towards this trope, as well as third person.
Tears of Remorse: Actassi, after the bloodbath, and killing Sherman.
Tempting Fate: Subverted. As Hetcher bemoans the failure of his attempt to steal the Careers' fever medicine, he says, "But it could be raining, right?" Unlike most times a character says something along these lines, it doesn't start raining.
Thoroughly Mistaken Identity: Very much not Played for Laughs. Diane, convinced that not only is Actassi Kali who is already dead, but that he somehow killed Hetcher. He's got no clue what's going on, and she is unaware of the mistake until shortly after she's killed him.
On the same vein, Franz kills Esther believing that she is the Career girl who murdered his sister.
Too Dumb to Live: If you know your teammate is a sociopath with a gun, what do you do? Hopefully not confront him about it on your own, as several of Lucian's allies did.
Too Happy to Live: Carden was taking everything incredibly well, until he was crushed by a giant rock. Whoops. If he had any foreknowledge, he would have tried to fit in one last smile...
"I'm looking for someone smart, strong, and not allied with my dear comrades from before. You know what, Lectic? Two out of three isn't half bad."
"Umm… You're right. It's only a third bad."
The Unfettered: Lucian doesn't care who he has to kill, what he has to do. But he doesn't exactly have a goal, just doesn't want to die.
Violence is the Only Option: Good luck getting out of the games without breaking a few necks... or skulls, or just plain indirectly killing other kids. Foxface couldn't do it, and neither can you.
Why Did It Have To Be Birds?: Dylan and Diele share a moment of distaste for avians in general shortly before they are set upon by a flock of terror birds. Diele thinks they are beautiful. Dylan disagrees.
Write Who You Know: Soren and Maren are based off of real-life friends of the author.