MILITARY
In Tales of Fandom: One Other Symphony, Yuan's personality and past shines through during Kratos' play through. The two walk through Gaoracchia Forest together to find fandalia flowers, and Yuan brings up their past in the military. The two were both affiliated with the knighthoods of two enemy countries. Yuan is originally from Sylvarant, and was known to be a high-ranked military official despite being a half-elf. Yuan was born in Asgard, though long ago he had another name besides for Yuan. At some point during his career, Yuan often met Kratos at the battlefield, and always claimed he hated him after noticing that Kratos never took interest in him, even if he was an unusually high-ranked half-elf.
At some point during his duty, the Sylvarant military was planning to attack the capital of Tethe'alla. Yuan, who was most likely leading the attack, received a friendly visit from Kratos. Kratos brings along two of his companions, Mithos and Martel Yggdrasill. Yuan notices that they were two half-elf siblings that were very aware of the attack that the Sylvarant army was planning on the Tethe'alla capital. Martel and Mithos both beg him to stop, but it is stated days later that they're attempt had failed, and the capital was burned down. We never hear whether or not Yuan ever agreed with Martel and Mithos or not, but one can assume that because of his military status and being a half-elf, he had to follow orders regardless of his personal opinions.