Lemuel Gaumon

Lemuel Gaumon was a remembrancer attached to the Thousand Sons, a scholar who learned too much of their arts on Prospero. He escaped the Wolves, sat in a Silent Sisterhood prison, and came out a vessel: a mind other people could wear, a notebook the Legion could not afford to burn and could not afford to leave intact.

Ahriman's brothers had treated him as a mascot with a camera. After the burning he was evidence, hostage, and tool in that order. The Pavoni and Corvidae both left fingerprints. Gaumon kept trying to remain a historian. The warp kept filing him under supplies.

Terra sent remembrancers to explain compliance. Prospero sent this one back as a warning about curiosity. He is not a Thousand Son. He is what happens when a civilian stands too close to a Fellowship and survives the lesson.