You may be looking for The Teller (Time Heist).

The Teller was the older brother of King Beol. He told stories of the King to the city of Geath. The Teller, on the Eleventh Doctor's arrival in Geath, told the Geathians a story that King Beol had won Teller from the people of Sheal. In the original story, Beol won Teller from the people of Dant.

During a struggle between the Regulator and the Herald for the "dragon", the Teller saw his brother (Beol) had a warped memory due to the Enamour hypnotising the people into believing their story. He assisted Rory Williams with the broadcast that persuaded the Geathians to give away their Enamour. (PROSE: The King's Dragon)