In 4126, the Ood brain managed to reconnect to Ood Sigma despite his link having been severed through the translator orb. Sigma was made a focus of the Brain's intelligence and mercy, and also its representative, in a sense. This allowed him to function as an individual and drug Halpen's hair tonic with Ood graft to transform him in to an Ood. For some time, Sigma had remained by Halpen's side while other Ood succumbed to red-eye. As Sigma was already reconnected to the Ood Brain, he was immune to the rage and anger which subsequently infected the other Ood. He led the Tenth Doctor and Donna Noble to the room containing the Ood Brain.