Killmoulis

A killmoulis can be either a bane or boon to an adventuring party. When kept well fed with tasty treats, this creature is a helpful assistant that mends armor, collects herbs that make the blandest rations into a feast, and turns a dull, uncomfortable campsite into a welcoming refuge. But if a party abuses or neglects a killmoulis, the creature's mean-spirited thirst for revenge can turn even the simplest expedition into a draining ordeal that leaves adventurers tired, dispirited, and sullen.
Traveling Fey. A killmoulis arises spontaneously in the Feywild whenever someone commits an act of charity to help a tired or lost traveler. Emerging from the shadows near the site of the deed, the creature takes to the road, wandering to seek out travelers who might have food it can sneak away with in return for the benefits of its magic. Shy and solitary by nature, a killmoulis enjoys watching and listening to folk from distant places that it knows little about. Whether fierce raiders, enterprising merchants, or bold adventurers, all travelers have something interesting to offer a killmoulis.
Hungry Helpers. Despite their odd appearance and origins, killmoulis crave the same creature comforts as many folk of the world. They adore sweet candies, fresh fruit, and other delicacies. When a killmoulis encounters a party of travelers, it hides and keeps a careful watch on them. At night, it sneaks into the travelers' camp and looks through their supplies for tasty treats, but will settle for rations, nuts, and other snacks. If it finds them, it quickly snuffles up a single day's worth of food with its long nose. In return, it then uses its magic to enhance the travelers' comfort as they rest.
A Bitter Reproach. A killmoulis will follow after any party that has provided it with a tasty snack, slipping into camp each night to gorge itself and pay for its feast with its beneficial magic. But if the travelers attack, interfere with, or try to trap the killmoulis, it places a minor curse on the group and attempts to flee. For the rest of the characters' journey, their rations taste like ash and any camping spots are infested with lice and biting insects. Each character in the party wakes up sore and cramped, as rocks or sharp sticks somehow end up under their bedrolls.
Once a killmoulis is angered, it continues to tail a group and visit its curse upon them. Only an offering of fine food and an earnest apology can sooth an angry killmoulis. Without that, these creatures hold a grudge against a group's rude behavior that can last for days.