What was the role of Joseph Parmuat?

Joseph Parmuat is first introduced at Ole Kaelo's welcome-home party. He is described as a handsome and intelligent young man widely respected by the people of Nasila. He is also a member of the Imolelian clan and considered a brother to Resian and Taiyo. He teaches the sisters about the customs and culture of the Maa people. Finally, he gives his life to save Taiyo, whom he loves.