Erethian originally possessed the gem, but Dracothraxus stole it from him (Erethian was thinking about getting it back, but nothing came from it). In Ultima VII, the Avatar was told about the Ether Gem by Arcadion, who thought that it could free him from his mirror. Erethian however knew, that it would only transfer him to a more mobile prison. The Avatar retrieved it from Dracothraxus after defeating her for the first time, and used it to bind Arcadion to the gem, fusing it into the hilt of The Black Sword.