King Ludwig II of Bavaria is known worldwide. However, little is known about his brother Otto. In the list of Bavarian kings, Otto is often forgotten or confused with his uncle, King Otto I of Greece. He becomes a footnote in Bavaria's history, as he spent more than half of his life suffering from a severe mental illness in Fürstenried Castle, without ever ruling. However, the life path of Prince and later King Otto I is just as exciting as that of his brother Ludwig. Who was Otto? How did he differ from his older brother Ludwig? What was the relationship between the brothers, and what significance did Otto have for Ludwig? Was Otto really mentally ill? These and many other details are examined based on verifiable facts. Otto received the same education.