* DieForOurShip: Amita.
* EnsembleDarkhorse: Oswald Kittner ([[Series/{{Undeclared}} Jay]] [[WesternAnimation/HowToTrainYourDragon Baruchel]]), a fantasy baseball player from "Hardball," was originally going to be another oneshot before fan reaction caused the creators to call him back for "Democracy."
* FanPreferredCouple: David/Colby. It seems like half of the fandom ships these two. {{Lampshaded}} jokingly by both characters in episodes in the fifth and sixth season. Especially in the sixth season, specifically the episode about the dating bet with Agent Betancourt and in the series finale.
* HoYay: In the episode ''Friendly Fire'', Colby, David, and Nikki make a bet on who would show up with the best-looking date; Colby and David win by declaring that ''they're each other's dates'' (Nikki lost when her date walked out on her after learning that she was the cop who arrested his friend for public intoxication when he was actually suffering from food poisoning).
** At the end of the season, David [[spoiler: is leaving for DC and everyone else refers to it as Colby and David's "breakup".]]
** When they're forced to spend time apart, Colby seems to go into withdrawal.
* TheScrappy: Nikki. She has a four year degree from the streets of Compton, yo.
* SeasonalRot: In general, the mathematics underwriting the solutions is sound, and explained in such a way as to remain at least a little accessible to viewers. During seasons 1 to 2, the writers were fairly good at keeping each episode theme-focused to illustrate a few related concepts or particular branch of mathematics, allowing them to give the math at least some decent coverage in depth. Unfortunately, as episode number climbed (especially in Season 4), the math degenerated into magical solution generators. The creators gave the series a minor retool around the midpoint of Season 5, now the math has been mostly relegated to a side show, and more personal drama are being pushed in front; most of the episodes in season 6 feature almost no math at all.
* TheWoobie: Charlie. There's a reason there is an ''entire subcommunity'' of fanfiction based solely around [[DistressedDude him and his Woobiness.]]
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