Gaius Amidonia

Gaius Amidonia is the father of Julius Amidonia and Roroa Amidonia and the crown prince of the Principality of Amidonia.

Gaius is an arrogant and prideful man, who carried a longstanding grudge against the Elfrieden Kingdom, due to the war 50 years ago, where Amidonia lost half of its territory. He followed a 'military-first' policy and waited for the opportunity for revenge against Elfrieden.

(Source: How a Realist Hero Rebuilt the Kingdom Wiki)