Man on Nathanial Carter Tape

In Episode 210, this unnamed man is interviewed on a tape given to Nic by Nathanial Carter. While he was only missing for less than a week, he believes he was gone for nearly a year, working in the great hall, the caverns, and other places Nic seems to describe during his hypnosis sessions. He says he spent most of his time working in a cold place, and had a girlfriend there. He mentions a presence that didn't want any of them there, a darkness...