An Imperial Knight who conceals a strong will under a gentle demeanor. Contrastive to Ernest Lyell, he always has an eloquent smile on his face. He is kind toward anyone and is deeply trusted by his subordinates. His merit as an Imperial Knight is considerable - when he wields his sword he will instantly consign his enemies to oblivion. He has a close friendship with master Richard and Ernest.

He fought against Carmaine at the bridge near Nostridge when there was war between Rolandia and Burnstein; prior to that he defeated a hundred Rolandian soldiers by himself.

(Spoilers)
Although he was loyal to King Richard, he noticed that Richard began acting strangely and possessed. He decided to support Carmaine and Lord Douglas in placing the real king, Eliotte, onto the Burnstein throne and end the war. Originally, at the time Eliotte was going to reclaim the throne, Oscar had wanted to fight until the end to defend Richard along with Ernest. They never wanted to betray him. However, they knew Richard was not normal, and one of them would have to support the enemy side for Richard's sake.

When Carmaine's group attacked Burnstein castle to take the throne for Eliotte, Oscar requested Eliotte to have mercy on Ernest and Richard. He wanted to fight Ernest one-on-one in the battle.