I don’t recall this character.
According to the IC wiki:
Risthart was the lord of Teirm before, during and after the Rider War. He personally swore fealty to King Galbatorix in the Ancient Language and attacked the ships of merchants who aided the Varden, such as Jeod. After Galbtorix fell, he demanded that Teirm become a separate city-state, under his leadership, but he had to swear fealty to Nasuada as High Queen.