Effuen, Evrains
The friendly, kind-hearted, and hospitable King of Brandigant who gave hospitality to Erec at the end of Erec’s adventures with Enide.
Brandigan was the site of an extremely perilous adventure called the Joy of the Court, supervised by Evrain’s nephew Mabonagrain, and Evrain tried to dissuade Erec from assuming the adventure. Erec, however, took on the quest and proved victorious. Afterwards, Evrain threw a celebration in his honor.
At the same time, there’s no indication that he was among Arthur’s vassals, or needed to be, seeing that the strength and self-sufficiency of his island fortress (possibly an outpost of the Otherworld) would reportedly have defied anybody’s siege. His name may be a variation of Yvain or Urien.
Sources
Erec | Chrétien de Troyes, late 12th century
Erex Saga | 13th century