After the fall of Ala Mhigo, the Garlean Empire continued their expansion campaign. Valdeaulin fought on the front lines, but was knocked out in the opening exchange. When he awoke, his entire unit had been massacred and the people his village, as well as his wife and daughter, had disappeared without a trace. After months of searching, Valdeaulin learned from two Imperials held at Bittermill that the villagers had been captured and used as test subjects for the poison gas that would later be known as the Black Rose. For twenty years, Valdeaulin wandered aimlessly, with nothing but hate to keep me alive, and joined the Order of the Twin Adder to take revenge on the empire.
During Operation Archon, Valdeaulin participated in the attack on the Praetorium. And when the place collapsed, Valdeaulin was caught in the rubble but managed to escape alive. While searching for a way out, he met Gaius van Baelsar himself, on the verge of death. Gaius asked Valdeaulin to delay his revenge until he had rid the world of the Ascian threat, and then after that Valdeaulin could take his life. Valdeaulin decided to grant the request and joined Gaius on his hunt. According to Valdeaulin, if the Ascians are really manipulating the empire, his revenge will not end until they are eradicated.
When Alphinaud's airship is shot down in the Burn, Gaius appears alongside Valdeaulin and Severa to help him. Gaius identifies himself only as "Shadowhunter" and says only that he is hunting the Ascians and that he has a history with the Scions of the Seventh Dawn. With no other travel options available, Alphinaud agrees to accompany them as he continues on his way to Garlemald.
The party stops at an outpost where they find several corpses, the remains of people killed by the Black Rose. Gaius scolds the Garleans for using technology he thought abandoned before admitting it was likely Ascian involvement. Gaius' group infiltrates the Black Rose production facility and destroys all the chemical stocks, even though it is only a temporary solution. During the infiltration they discover a series of cloned bodies of a young Emperor Solus. Eventually Alphinaud loses consciousness and Gaius personally takes him back to the Scions, where he reveals his findings as well as information about Emet-Selch and the Ascian hierarchy.
Gaius and his companions continued infiltrating and destroying the Magitek facility to destroy the Black Rose vestigius. Eventually Estinien invades the same facility as them and after meeting, they and form a temporary alliance. They infiltrate the Imperial Palace in the capital of Garlemald only to find a trail of bodies and Gaius asks Severa and Valdeaulin to find out what had happened. Gaius and Estinien storm the throne room and discover that the person responsible for the massacre was Zenos yae Galvus, and they witness the murder of Emperor Varis zos Galvus. While escaping from the palace, they find out about the resumption of the Weapons project.