Unknown, also referred to as Subject Not Found is the "narrator" of Transistor. He sacrificed himself to save Red's life, and as a result his consciousness was absorbed into the titular Transistor. It is heavily implied that he and Red were in a relationship before the events of the game. He is voiced by Logan Cunningham, who also voiced the narrator in Supergiant's previous game, Bastion.
As Unknown spends the game inside of the Transistor, he is never seen until the end credits. His face is always mostly obscured, but other parts of his body are still visible. He is taller than Red, and has short black hair. He wears a jacket with a yellow equilateral triangle on the back and sleeves that go down to his elbows, which Red wears for a majority of the game.
Error: Subject background data corrupted during integration. Reason: Unknown.
Recovered data indicates Subject had no Selections on record. There is a remote possibility (less than 5%) that this information is inaccurate due to data corruption. In the more likely event that the information is valid, Subject by definition cannot be matched with the census data, as 0% of Cloudbank willingly chose nonselection.
Timestamp on Subject's integration coincides with timestamp of previous authenticated User relinquishing access and control. Although Subject's trace data was corrupted during integration, nonetheless such data has it's uses, and consequently derived a suitable Function. Subject's trace data remains disjointed and cannot be recovered.
- In the game's files, he's referred to as Auden. This could be a hint as to his true identity.