Quintus is a Champion soldier found upon entering High Hall in the Orobas Fjords. His Marching Orders can be found on a table outside Nicolas' house. You are sent to aid him during the quest Between a Troll and a Hard Place, assigned by Lieutenant Brutus. After a few words with Quintus a couple of trolls attack. After dispatching them, the conversation continues and he assigns the quest The Runes of Wrath. If you ask him to send men with you, the reward for Between a Troll and a Hard Place can be different, see the article for details.
Mindreading him yields no reward, and reveals: "Quintus can`t stop thinking of trolls, which annoys him tremendously."