The hero is serious, taciturn, and finds mirth tiresome. He’s Provoked on any successful Taunt—whether the opponent has the Provoke Edge or not. Provoked characters subtract 2 from rolls to affect any opponent except the one who insulted him.
This lasts until a Joker is drawn (by either side) or someone else successfully Taunts the dour ruffian.
Grim also counts as a Requirement for the Menacing Edge.