Found on Rub Al'Kali (RAK) in the past by Cromwell's away team, Brinn admits to having lived on RAK for at least 15 years.  Planetary effect slow growth significantly, so those years unlikely added any apparent chronological age.

Brinn is Six's Primary command source, and seems fully content to use her as any other tool at his disposal.  He once used her to erase the crashed 'The Jersey' ship's logs to erase "El's" history to protect her, then having Six erase her own logs of the event.  He also convinced her that the Marine Terros had put her into cryogenic suspension for three months, when it had been three days, just to see if he could.

Six has trained Brinn to become an expert in Borg, Borg Philosphy and tactics and how to defend against them.  Brinn has taken considerable interest in these studies.

Brinn has taken interest in several of Cromwell's crew, but is finding being closely aligned with six is interfering.   However, Brinn's need of Six of Twelve matches her own for him, and this makes him protective of the Borg Drone in his care.