Greater Good is the second book in the Thrawn Ascendancy trilogy by Timothy Zahn. It's a fairly unique entry in the greater Star Wars canon in that it exclusively explores Grand Admiral Thrawn's past in the Chiss Ascendancy. The Ascendancy exists completely outside the realm of the Republic or Empire.
Chaos Rising is the latest Thrawn-focused entry in the Disney Canon series of Star Wars novels. Again written by Thrawn's creator, Timothy Zahn, Chaos Rising serves as the first book that truly explores the Chiss Ascendancy prior to Thrawn's encounter and joining of the Empire. The first Thrawn trilogy in the Disney Canon explored Thrawn's rise to power leading up to his inclusion in the Rebels animated series. In this newest trilogy, Zahn will be turning back the clock even further to focus on Thrawn's earliest military days and the political and military inner workings of the Chiss Ascendancy.