The younger twin brother of Devonn Tweedle, Dummac (better known as Dum) was a member of Na'Ka'Ve's local Oglaigh na Tír chapter, and in a relationship with Mariah, the exhibitionist barmaid of the Golden Goose Inn. He and his brother were largely identical and only really able to be told apart by Dum liking to wear red and not having a beard.
Dum, along with Mariah, was accidentally killed when they were caught in the blast of an upcast Fireball fired by Rilira Fl'wr which destroyed Brant the Lost's office in Na'Ka'Ve City Hall.