Poisson is a very important supporting character in Tales of Graces f. She is very close to the Amarcian Overseer, the elder of the Amarcians living in the enclave. She is the next in line to become the Overseer.
Asbel and team meets Poisson for the first time outside the Overseer's Chambers in the Amarcian Enclave, hoping to access the Archive of Wisdom to obtain more information about Lambda. Poisson speaks directly for the overseer who is very very old and denies them entrance. She appears again after the party defeats Kurt at Fendel's valkines and tells the team that the Overseer has now allowed Pascal and party to access the Archive.