The simplest advice for writing unsympathetic characters is to think of the traits that make it hard for you to sympathize with real people.
What is Fo’Fonas, Anyway?
About a year and a half ago, I had an idea for a magic system, inspired by how a relatively primitive culture might perceive the four fundamental forces of nature. Just to explore the magic system, I decided to write an expository scene. When I finished, the scene was almost twenty pages long, involved the main character climbing a really, really long staircase, and I realized it was chapter 1, and that I had a chapter 2 to write. About seven months later, I finished the rough draft of what I realized would become the first novel of an epic fantasy series.
IGC Publishing 