Goeth, from Ultima V: Lazarus
When meeting Goeth in Ultima V, the Avatar found his speech to be very bizarre as he often spoke words backwards and out of order. So the Avatar inquired of the other citizens of Jhelom about him, and was told that this was caused by the Oppression. They tried to extract the Word of Power from him. That coupled with the isolation of Jhelom drove Goeth to madness. He was freed when the Oppression learned that his tenacity was greater than theirs.
The Avatar learned from Trian that Goeth sometimes needs to hear words backwards, thus managing to get through to Goeth, who then revealed the word for the dungeon Destard. He also revealed how to excavate Moonstones, something he'd learned before being arrested.