Ragu describes him as "cunning and manipulative" during the quest Four Brothers, One Kingdom, which is shown when Karl attempts to turn the player against Childerich IV. He is the most well-mannered of the four brothers, and seeks peaceful solutions even when the player shows hostility.
After defeating the tyrannical Queen Kaiserin Konstanze, the player is urged to scout the provinces south of Kaiserin's kingdom, revealing that Breturia was ruled by Karl.
After taking over Veletrites, the player must choose to side with either Karl or Childerich IV, who are currently battling each other. If the player decides to side with Karl, the player would then defeat Childerich. If, however, the player chooses to side with Childerich, the player would defeat Karl, only to defeat Childerich later on in order to reach Moravaria.
His surname, "der krumme," literally translates to "the crooked" in German, which likely refers to his crooked posture. This name implies that he is of Germanic origin; however, both he and Childerich wear what appears to be a fleur-de-lis, a symbol associated with the French.
The Story of the four brothers reflects actual history and custom under the Frankish Empire. Charlemagne had one son when he died, so his son became Emperor of all the lands of the Franks this was all of Austria, Belgium, Luxembourg, Netherlands, Slovenia, Switzerland & France (except Brittany), Spain north of the Ebro, Italy as far south as Rome (except Venice), Germany to the West of the Elbe, However Charlemagnes Son had 3 sons when he died and the lands were split between them.
As Charlemagne was the first King of France (Gaul being the Roman name for the area) and Holy Roman Emperor, it is possible for items associated with one country today actually to come from the Franks and their dominance of Western Europe at the time.