Weird quirks the monsters in my Crowded Sea campaign (probably better known as #boatmode) have picked up over the years:
Many oozes have a minty fresh smell and gelatinous cubes shatter into hard glass shards when dying. Chris asked what smoking those remains tastes like. That has actually been explored in our game. It tasted like crypt floor dust from all the gross blood and bones they’ve been vacuuming up. Various oozes are made from different things (they don’t all share the same etiology) but gelatinous cubes specifically have been pretty well studied by alchemists and there exists potions to turn oneself into an ooze (from The Scarlet Citadel).
Skeletons enjoy saying “ri ri ri ri ri ri ri!” to somehow, uh, strike fear into their foes. With mediocre success. But they really like doing it. Probably their favorite thing to do.
Kua-Toa refer to mermaids as “inverted” merfolk and see themselves as the proper kind.
There are four separate kinds of lizalfos. From Hot Springs Island we have Kiru, Arva, and Goa—the latter are (I’ve decided) the same as in Danger at Dunwater and are considered enlightened in the Land of Fate after they adopted a kahinic faith thanks to diplomatic efforts of one of the player character parties. And from Arden Vul we have the Skreel kind.
There are also many kinds of mermaids since we’ve used a ton of modules with them. Neverland, Uncaged, Trilemma all have their different spin and I liked them all enough to deliberately go against my normal policy of consolidating overlapping monster types. (For example, “blood moth cultists” have shown up in many unrelated modules since, because it’s such a powerful and broad trope.)
Goblins are not all goblins. Instead, “geeba speakers” refer to the urchin underclass of cities, a mix of species (goblins, humans, halflings, the occasional tabaxi) who have adopted the geeba language that the goblins brought to the Land of Fate.
Pumpkin-heads refuse the slurs “bugbear” and “jack-o-bear”. They are neither bugs nor bear, they have a feywild heritage. They wear magic helmets made out of pumpkins.
Dwarves use the singular “dwarve” (rather than “dwarf”). Ladies wear their beards braided with perfumed oils.
Elves have ears that look like they’re out of the Japanese version of the Rules Cyclopedia, or like Deedlit from The Record of Lodoss War.
My dorks don’t know this one yet (I’m OK with them learning it this way): Trolls are to elves kind of what liches are to humans: a result of trying to prolong life by forbidden magics.
Ælf-Adal (from Veins of the Earth) are replacement for drow, but they are mashed up with drow I guess because I’ve always had a soft spot for the original spidery crew ♥︎ (loved the sluagh in World of Darkness).
Fruit hounds restore 2d4+2 hp if eaten or can be used as a component for a raise dead spell (in lieu of other material components—you still need the spell. The leaves from their trees (which are catastrophe trees according to Fire on the Velvet Horizon; catastrophe trees plague the entire Crowded Sea these days) have effects as per the Sipopa table in Hot Springs Island, but, unlike that table, you don’t need to prepare the leaves especially (Sipopa is notoriously difficult to manifacture), you just need to smoke ‘em. Common among pirates and especially among Flamesea mages. Fruit hounds replace sun fruits from The Sunless Citadel. (I know the FotVH gang can get a li’l grumpy if you overly explain every mystery in their book, even more so if it’s in a way counter to what they had in mind, and I can def relate to that, but this is more of an AP report of what the canon is at our particular table.)
