Soren was a fisherman and one of Lofoten's few survivors after the Wild Hunt attacked the village in 1272. He liked to call himself "the Elder", and was a little too proud of himself despite losing three sons in the massacre.
He is the old man who Ermion mentions during the closing dialogue of Echoes of the Past, and Geralt and Yennefer can question him while following Ciri's trails in Lofoten, but he isn't helpful.