Who is Marcus Valerius Messalla (Rufus) from Roman Blood and what is their importance?

Marcus Valerius Messalla, also known as Rufus because of his red hair, is a young Roman nobleman. As a member of the ruling class, Rufus has the bearing and demeanor of someone far older than his sixteen years. As brother-in-law to the dictator Sulla, Rufus has access to people, places and things that other nobles do not. Physically, Rufus is described as tall with a ruddy complexion, brown eyes and a freckled nose.