Winterhoof Brave is a special form of the Camp Winterhoof Brave, the guards of Camp Winterhoof, he is summoned to aid you after doing the quest Skorn Must Fall! and recieving the Winterhoof Emblem. He will aid you in three missions, Gruesome, But Necessary, Towers of Certain Doom, and Burn Skorn, Burn!.
After all three missions are complete you are to return the emblem to Chieftain Ashtotem, although as long as you carry the emblem you can re-summon the brave to aid you in fighting while in Skorn. After you return the emblem you start the The Conqueror of Skorn! questline.
It might be a good idea to keep the emblem a little bit longer before returning it as the brave will help you fight any Vykrul you encounter, helping your character level up faster.