Cerses, Secies, Serces, Sers; Serse, Xerxes
King of the Vermeil Castle (Red Castle) and the castle Pagon. He served King Claudas. The Vulgate calls him,
le conestables du Chasteau de Pinegon.
King Bors of Gannes, Lancelot’s uncle, had killed Serses’s brother, so Serses became Bors’s mortal enemy. When they met in single combat, Bors defeated him and took his crown. Later, his castle at Pagon was conquered by Arthur during Arthur’s invasion of Gaul. Serses managed to escape the siege in time to warn Claudas of Arthur’s advance.
Source
Vulgate Lancelot | 1215-1230