He lives only to find challengers worthy of his blade and will kill opponents in battle without remorse or hesitation. To obtain the infamous Wo Dao, he murdered his entire family, with the exception of his sister, whom he saw as no threat at the time. His feats — including fighting armies alone and slaying a wizard that could freeze blood in a person's veins and killing a stone giant who was three times the size of a regular man — have earned him infamy across Elibe, as well as the title of "Sword Demon", revealed in a Support conversation with Dart. He is Karla's older brother and also taught Guy swordplay.
The Binding Blade
Karel becomes the uncle of Fir, the daughter of his late sister Karla, after her marriage to Bartre. He retired from active combat and traveled the land with a new nickname, the "Sword Saint", and resolve, having finally found peace in himself after many years. He appears to dislike the title he was given, claiming it is a false name, perhaps because of guilt for his past actions. Bartre married Karla, which makes Karel and Bartre brothers-in-law. He has no real interest in the overall state of the world around him, only joining the fight on behalf of his remaining family.