Koftik features heavily in the Underground Pass quest. In the quest, he is a guide through the pass, teaching people how to make fire arrows to enter it and showing up in various places throughout it. When spoken to in most of his locations, he will provide the player with some food because "it is a dangerous area." You may have to wait for some time before he will give food again if you've already taken some.
During the quest, he slowly starts to lose his mind due to Iban's influence. Once Iban is destroyed, he regains his sanity and can be found in the room of the Well of Voyage (after starting the Regicide quest).