Citizen of the Galaxy (1957) – Thorby, a very young slave boy, is bought at auction by Baslim the beggar and adopted as a son. When Baslim is killed as a spy by the local police, Thorby discovers that he has prepared for Thorby to escape. He goes first to the Free Traders, then to the Hegemonic Guard space navy. He never feels at home in any of these places. Least of all does he feel at home when the Guard delivers him back to earth, to inherit control of the interstellar corporation which might have caused him to be enslaved in the first place.
For more information on Heinlien's Juveniles (written between 1947 and 1958) see our entry on Robert Heinlein's <…
Patterson, William. "Citizen of the Galaxy". The Literary Encyclopedia. First published 10 November 2004
[https://www.litencyc.com/php/sworks.php?rec=true&UID=16615, accessed 18 October 2017.]