Mattson Tomlin 
Vicious Circle, A #1 [PDF ebook] 

Shawn Thacker is a trained assassin from the future who seeks revenge on the only other man with his affliction-each life they take forces them both to travel between vastly different past and future eras. Spanning from 22nd century Tokyo to 1950s New Orleans to the Cretaceous Era and beyond, the two mortal rivals are locked in a battle of wills that spans millions of years, all to alter the course of history.