Eldernymph
Eldernymphs must always stay within 100 yards of an elder tree, but they can close their eyes and stay still for three seconds in order to instantly travel from one elder tree to another within a mile. Eldernymphs are the wise women, healers, and leaders of faerie communities in the forests. The used to be nymphs, and they likely have many daughters. Should something happen to her or her home tree, one of her daughters will take her place.
Elder trees are sacred to the fae. Burning elderwood, destroying an elder tree, or taking too much from one tree, or taking anything from the tree without seeking permission first are all punishable offenses. To ask permission, you can first try to speak to the residing eldernymph, but you probably won't get an answer. If you don't, place an offering of food at the base of the tree. If the food rots, do not take from the tree. If the food is eaten and there is a gift in its place, then you may take from the tree.
When encountering an Eldernymph, assuming you haven't done anything to offend the forest, their default demeanor is motherly.
The Eldernymph for the island is named Aghavilla, and she has cared for it for over 1000 years. When you step into her glade, you step onto the branch of a large elder tree (or perhaps you are an inch tall? It's a matter of perspective). You can explore by walking and climbing on its branches, which are often wide enough for three people to walk abreast without being worried about falling. If you do fall, Aggy's giant hand catches you and places you back where you were, almost like a Mario Kart whiteout.
Abilities
Nymphs are incredibly observant and perceptive, and they can blend into the scenery at will. They will likely use Seeming to appear as a human when interacting with mortals. Tree Nymphs can commune with plants and animals, and they excel at plant-based magic. Eldernymphs are powerful enough to create Faerie Glades for others to hide in.