Ludwig is often nicknamed as "Lui" by the people around him, though most still refer to him as Ludwig because they are afraid of him and respect him. His title Herzog is the second highest title among the nobles, and means Duke. His father is a Duke as well, but his mother is the king's sister, making the king of Kuchen his uncle. His other uncle on his mother's side is the king's (rebellious) younger brother, Helbert. His uncle on his father's side is Camus' father, making the two of them cousins. It is known that he has two housekeepers, Augusta and Clemence, a younger sister and a younger brother. Also, he is left-handed.
Lui appears cold-hearted most of the time. He is very arrogant and yet he knows what is expected of him by his rank and position in the world of those times, and accepts it with cold indifference. He often leaves his friend shocked at his words when he voices his thoughts. However, Lui is a good judge of character and seems to know what to say to help the people he is fond of solve problems on their own. He likes challenges, as long as they are fair towards both ends. Lui claims he is not like the others, insinuating that he is cold hearted and calculated, and compares himself to Orphe by saying that he can not grasp an opportunity and fight for it like Orphe does. Isaac reprimands Lui for his way of thinking, claiming that it was too dangerous.
Source: Wikipedia and Meine Liebe Manga
