The Archivist is was an inmate of the Moira Asylum. He is patient #31 and is a thief, and has uncontrollable urge to steal. Very little is known about his life previous to being committed.
It is as least known that he appears to like to 'collect' things has undergone electrotherapy treatment, and he sees the Sneak Thief as a like minded individual. During his time at the asylum he was first kept in the Men's ward, but it's known he didn't work to well with the staff, and kept on trying to escape, with the help of The Watchman. He was later moved to another location to separate them, and so that the staff could keep a better eye on him. Still he managed to escape a few more times.
During his various escapes he discovered secret caches put in place by the Sneak Thief, and he himself may have put together his own stashes of things he took from other inmates and staff. After discovering the first stash he began to hear clicking and beating of the Sneak Thief's Mechanical Eye as if it was still beating heart.
During one his raids he stole the key leading to the women's ward (after it had been moved to another room to keep The Dancer from using it), and hid it away in an unused room. He is also one of the inmates that Erin's Primal influence had an effect on, possibly agitating him to more larceny.
His last whereabouts involved an escape down into the treatment center, and into a vent leading down into the Old Prison. He discovered the Sneak Thief's last treasure stash in the vent, and was getting close to the beating Mechanical Eye, but he decided to rest there. He presumably was transformed by Erin or killed by the former inmates that had become The Freaks just short of the Old Prison and the Mechanical Eye he desired.