Guhrr is a Thahd (a particularly strong Thahd) who, along with a gaggle of rogues, commandeered Captured Bridge, to put it simply. Guhrr can be convinced/commanded to step aside for you if your leadership skill is high enough. If he does, him and the other Thahds cross the bridge and Guhrr says "I... I go now! But I am strong! If we meet again, you will pay!"