Edgar is the father of Gart, and uncle of Gwendolyn. Edgar lives with Rosella and his son primarily in Daventry. Rosella was always off on her own adventures with Edgar. He is presumably still from Eldritch.
Behind the scenes
He is first mentioned by name in Chapter 4 in the game, but alluded to in chapter 1. He was previously only mentioned by name in an article in GameInformer. His whereabouts are unclear so far. His background is not mentioned, nor his fairy heritage. Fairies in general are downplayed in this series, and most references to them were cut. That which does exist, does not appear to resemble anything remotely like fairies of the original series, see Fairy.
In Reboot Canon, Rosella and Edgar finally marry, and Rosella gives birth to their child Gart, cousin of Gwendolyn. Gart believes he is to be the next heir.
Edgar is only alluded to indirectly in chapter 1 but not by name (but he does get a mention in Chapter 4). It appears Gart's family lives most of the time in Daventry. Other than that Edgar is only mentioned directly by name as the father of Gart in an article in GameInformer.