A former Borg drone, once Four of Nine, who shared a damaged collective mind with two other survivors from Seven of Nine's crashed scout ship.
P'Chan is the third of the former drones who come aboard Voyager in Survival Instinct. As Four of Nine, he was assimilated into the same unimatrix as Seven of Nine and survived the crash of their scout ship, after which the four drones began to recover their individuality.
Seven, still loyal to the Collective, reassimilated the other three before the Borg arrived, a memory she recovers only by linking with them. Years later, P'Chan's mind remains bound to his companions, until Seven asks the Doctor to free them at the cost of a shortened life. P'Chan chooses to spend his last days on a nearby uninhabited planet.