Canonically, Caro is actually avidly against using magic. It's later explained that he was used to killing during his late adolescence. His peers consider him one of the top of his class so they felt like he was wasting his talent giving it all up. In contrast, Opeca Caro dreams of learning magic

because the war never happeend in opeca, caro was never ""Abused"" into the military. But instead he is left with a sense of longing for family and unity, which every splendor user happen to have