Chessa is an Undead Vampire Spawn who is imprisoned in Cazador's Dungeon. She is one of the children recently kidnapped from the Gur by Astarion and forcibly turned into a vampire spawn.
As the party progresses through Cazador's Dungeon, they inevitably pass by a prison containing various Vampire spawns, including Sebastian. When talked to, Chessa comments that she smells fresh flesh, and tells herself to snap out of it as the urges from being a vampire spawn begin to take hold.
She then asks the party to have mercy and put her and the other children down, as the hunger is becoming too much. If Cazador is later defeated, the party can then choose to consume the souls of all vampire spawn or free them, the former resulting in Chessa's immediate death. If Chessa is freed, she can later be seen in the Lower City Sewers with her father Gandrel.