I’m fascinated by gremlins in Pathfinder, because I just can't peg down the design philosophy behind them. There’s no “default” gremlin, like there was in the world’s oldest role-playing game—jinkins kind of have the look, but it’s the insectile vexgits who have the usual hatred of machines. (And let’s be real: The real default “gremlins” in Pathfinder are its iconic goblins anyway.) Pathfinder’s gremlins also don’t belong to any one tradition like, say, the oni, or have a coherent feel despite being borrowed from all over, like psychopomps. Instead they’re a mishmash of physiognomies and abilities, both real (that is, from our world’s folklore) and imagined. It’s like someone mixed up the Lego collections of Brian Froud, Charles de Lint, Jorge Luis Borges, and Jim Henson all in the same bucket and built whatever came to mind.
That’s not a knock against them; it's just interesting—they're a monster family that defies easy categorization and ordering…just like gremlins themselves.
So creating a gremlin out of Jenny Haniver, a Cockney name for a bizarre Belgian tchotchke (and I say that as a bizarre Belgian, if only by birth, myself) made out of a mummified skate? Sure, why the hell not?! And the fact is, it works, because the haniver is instantly real-feeling in its own right. I don’t question that it’s an actual creature because…well, it kind of is.
Every gremlin has a focus, and hanivers are about stealing little treasures and objects of value. That precious thing of yours that nevertheless managed to lose itself?—a haniver’s doing, courtesy of its misplacement ability. The intrinsic worth of an object means nothing to a haniver; it's another creatures desire for the object that gives stolen things value to the fey.
At CR 1/2, hanivers are great aquatic/coastal encounters for PCs just starting out. A fishing village’s annual haniver hunt is not a bad way to throw together a disparate group of PCs. And since hanivers are congenital thieves, they can land PCs in hot water with the law at a low enough level that 1st-level fighters are still a threat PCs will have to take seriously.
It’s Hope Harbor’s annual haniver roundup. Teams of boats go out to catch as many of the troublesome gremlins as they can. Even landlubbers get into the act, as having a properly prepared haniver hung on your door is meant to ward off ill luck (or at least, more gremlins). But this year’s hunt is fouled by a boating accident that may be a murder, sightings of the mysterious shoal elves, and rumors that the hunt has angered Magatha the Sea Witch…not to mention swarms of hanivers that prove exceedingly difficult to net or kill.
A dwarven thane demands to see a mermaid, pointing to a relic of his old adventuring days: a dried and shriveled haniver. He may be off his shop stool, but he strong-arms a group of young adventures into hunting for “mermaids” with him. When they actually do face the troublesome gremlins, he slips away…off to meet a mermaid he fell in love with in his youth, whom he has secretly and faithfully visited every 20 years since.
Usually hanivers steal trinkets of little value to anyone but their owners. But when a haniver overhears a power-hungry noble covet a young prince’s signet ring, it cannot resist the theft…and inadvertently causes a crisis of succession. Now the prince’s guardians and the noble’s retainers hunt the ring and each other. The haniver realizes what he’s done can only cause trouble for him and his kin, but the more desperate the searchers get, the more his fey nature refuses to let him return the ring. Talking the gremlin out of his prize possession may take a lot of diplomacy…but it’s nothing compared to talking one’s way past the noble’s men without being searched and detained.
I should mention that participating in a haniver hunt might cause PCs some alignment troubles, as they are neutral creatures and reasonably intelligent to boot. That also might make the custom of nailing dead hanivers to one’s door a bit troublesome. If you want to avoid those dilemmas, you can just have the greedy and territorial fey attack the PCs…but if it’s an experienced group of players, make ’em squirm a bit if they attack the fey without talking first.
More on the haniver can be found in Pathfinder #25: The Bastards of Erebus. That issue also gave us the Pathfinder version of the rot grub, our first look at the strix, and the torble, which a reader asked me to do adventure seeds forever ago. (I will get to it! Eventually!)