I'll rather let some logs define him because I am tired of reading fictional things about characters which I never actually experience a trace of in-game:

• SunPoetryWithCeinna - Sun and Ceinna reads poetry and Sun finds out some things about Ceinna's life that he dislikes.
• SunSpeaksWithJudgeTehanu - Sun urges to Tehanu about a new law proposal.
• CeinnaAndSunInTheGardens - Sun stays with Ceinna in the "gardens", but it does not go entirely as he planned.
• SunEncountersElfGirlInArborea - Sun meets a young girl in Arborea who claims she spent the night there, so he takes her to Elvandar to live with her people.