Gordon R Dickson 
Wolfling [EPUB ebook] 

A hundred years in our future, the first expedition from Earth reaches Alpha Centauri only to discover a vast human empire, long-established and sternly ruled by the aristocratic High-born. In a stroke Earth becomes merely another primitive outpost, its people dubbed "wolflings" by the rulers of the Throne World. Painstakingly chosen and meticulously trained, Jim Keil was sent merely to observe conditions on the Throne World. The High-born would consider him no more than a diversion until Keil cast away his orders from Earth and proved a Wolfling indeed.