[Lalaith]

An aside about Arthur and the Picts:
Arthur has no children. Gawain, (and Gareth and Gaheris) one of the earliest knights/heroes to be associated with Arthur, is his nephew, the son of his sister. The would-be ursurper Mordred, another very early element in the Arthur legend, is the son of Morgana le Fay, often described as another sister of Arthur.
The Picts practiced a curious pattern of inheritance: the kingship was inherited through the king's sister, so the nephew, not the son, would be the new ruler.


But back to the Norse: I've mentioned before the notion of the "dark hero" in saga literature, which always reminded me of the cursed children of Hurin. (Grettir the Strong, for example, wrestled with a ghost called Glumr and was cursed by him, after which nothing ever went right for him and he became an outlaw.)

The Valar seem more like the Aesir/Vanir to me than the Graeco-Roman gods. For example, Vaire, the weaver who depicts past, present and future, is reminiscent of the Norns, who weave fate into their tapestries.