Why Vauthry? Why not Vauthry? Seriously, looking at your signature alone, this is the character you choose to clutch your pearls over?
He was corrupted before birth and groomed to a very specific task.
a.k.a, to be a stopgap to keep the Light from overtaking the First before the Rejoining could happen. There's no reason to believe that Valens van Var--er, Emet-Selch would corrupt this infant, only to then say eh, grow up to do what you want, go fight those Sin Eaters. Instead, the child was brainwashed to believe he was the protagonist of the story, and anyone who came against him were "villains" who must be stopped. A lot of people love waxing on how terrible it was for their WoL to come this close to losing themselves to Lightwarden corruption. How is it any less terrible for a child who had no blessing of Hydaelyn, and was being fed lies to make sure they performed their part in the Ascians' plan?
Cylva confirms the Ascians were not passive players in Eulmore. It was the Ascians' idea to raise The Virtues, and it was the Ascians who left Gaia an orphan alone in the city.
The Virtues, who behaved in a way that completely twisted how they were in life, as Titania went from a beloved ruler to being kept in the cramped old castle. As Tesleen tried to kill us, as we would have killed our friends had we not contained the Light. Light corruption has never left the victim unscathed, but for some reason, you expect it of this character, since birth. Why?
To his dying breath, he didn't understand that he was not the hero he was groomed to believe he was. But he needed to be convinced he was doing good, twisted though it was, when he had the power to not care at all.
Even the Exarch said Vauthry's hope was "to vindicate his existence".
Yoshida asked players to consider was Vauthry really a friend of the Sin Eaters, or was he controlled by someone.
Vauthry was a tragic character, and considering they had to convince him he was the good guy, he probably would have been a much better ruler than his father, if the Ascians hadn't corrupted him. But Emet-Selch never gave him a choice to be anything other than what he was created to do.