Faeries are beings of light, children of Aurus the White Sun. They are native to the floating isles of the Astral Plane, where his radiance never sets, and they are made of that light rather than of any current of the Material world below.
They cross down only during Faesummer. When Aurus drifts near the Material boundary and warmth sweeps across Alaria, faeries spill into the world alongside the Sprites, the Nymphs, and the rest of the Astral kind, scattering through forest and field with light and a season's worth of chaos. When the Sun draws off again, they withdraw to the isles.
A faerie can hear Faesong — Melera's emotion-current running under the living world — and channel it to work small magics. This is the thing that has confused mortals for as long as there have been faeries to meet. The forest fae, the pixies and Faeja and the spirits of spring and grove, are Faesong itself condensed into flesh; they belong to the deep reservoirs and answer to the Queen of the Forest. A faerie is none of that. It owes the forests nothing and the Queen nothing, and it is no more made of the song than a druid is. But a creature woven of soul-light sits close to the emotion-substrate of Ezz, close enough to catch Melera's melody the way a druid or a bard catches it — and hearing the song is not the same as being the song. Mortals who met small luminous song-hearing things abroad in the warm months lumped them in with the forest fae, and called both fae. The word records a resemblance, not a shared origin.