Leshy is the silf of Limbo, realm of the Giants, as well as the progenitor of all Lycanthropes. Leshy, just like all Silfs, is the manifestation of the its realm and more importantly, its axis mundi, in this case Langgan. From time to time, a planar tree may change its Silf, for a variety of reasons. Perhaps the Silf was killed or the tree itself felt a change was needed as a result of changing beliefs. In the case of Leshy, it was the latter, as life on other planes developed and expanded, Langgan sensed an imbalance between nature and civilization skewing more towards civilization. In retaliation, it created Leshy, a vengeful spirit focused solely on protecting nature from widespread destruction at the hands of those who seek progress at the cost of nature.
Leshy, in turn, imbued its vengeful spirit into a rune and planted it throughout the realms. Harmless to the trees, rocks, and animals it imbued it on, it was not so kind to people when they were bitten or spent enough time around Leshy’s rune. Instead, it turned them into the first Lycanthropes, a gross corruption of the person they were mixed with the animal that bit them or the environment imbued the rune. This curse warps the mind of the afflicted, turning them into an agent of Leshy, protecting nature and seeking out vengeance on civilization. The curse reaches its height during a full moon, when power from the realm of Limbo is also at its peak. Usually at the beginning, the afflicted can stave off the curse outside of the full moon, but the longer they deal with it, the harder it becomes to separate the two sides of their personality, and may transform on nights without a full moon or even during the day, or may live in a hybrid form. Still, there are those who manage to conquer their curse and reap the benefits of it while avoiding its downsides.