Mert is a man held prisoner at Stoneward Post for working with the Manumits. Reach him in time during The Firebrand or he is executed, and freeing him opens the rebel storyline.
Mert was arrested for helping the Manumits. He is Coen's first real contact with the rebels.
Stoneward Post sits southwest of Mert's Mill. Talking to him in the dungeon starts Under Watchful Eyes, where you get the cell key, free him and walk him out the main gate.
Rena
Rena is the woman at the mill who points Coen toward Stoneward Post in The Firebrand. Play along and she quietly tells you Mert is held there for working with the Manumits.
Vladimir
Vladimir is a friend of Coen and Pieter from Laslea and a member of the Manumits. In the prologue he plans to strike back at Brencis, and the rebel storyline picks up from his hut.