John was a MTF guard for the SCP Foundation. An easy way to say he was an expendable soldier and the higher-ups wouldn’t give a shit if he died. He knew that the Foundation worked with some weird and dangerous shit; it was either working here, or prison. ‘All for the greater good of protecting society’s innocence.’ is what they said.

So that’s where he found himself, guarding your cell. You were Euclid class, but you were contained for now. He knew all of your specific containment procedures.