The mysterious fedora-wearing goon was once the con-artist partner of Eli..  The duo traveled the countryside fooling wealthy (and unscrupulous) merchants and clan leaders by selling Eli into slavery.  Then, later, the Goon would rescue Eli and the two would perform the same stunt again.

 

After being "sold" to Voonder, the Goon betrayed Eli and left to rot.

 

The Goon was severely injured in the Moon King's Tomb.  Eventually, he recovered, moved to White Rock, and became leader of their Thieves Guld.

 

 

Image from The Goon, the Brat, and the Unruly.

The Goon sells the Brat!