User blog comment:Morganaforever/Morgana's torturer in 5x08/@comment-5674726-20121117214304

Based on Morgana's reaction when she realised that Guinevere had no idea that she had been held captive, I'm leaning towards her torturer being either a known ally of Arthur's or somebody who claimed to be an ally of Arthur's, and possibly to be acting on his instructions, or at least with his knowledge. It seemed like she had assumed that Guinevere was aware of what happened to her until Guinevere's reaction showed that this was not the case, and she may still believe that Arthur knew and approved.

Whoever it is, I hope there's not enough of them left to bury by the time she's finished.