The Brotherhood of the Brawl

An organization that spans all over the continent of Astapor. From underground fighting pits to hidden spots in a nearby forrest, The Brotherhood is everywhere.
The Brotherhood is basically fight club. It is designed so members can find friendly faces in new places. Members get together to share information, gather as a group, and have sparring matches. 
Anywhere that bares the symbol of the Brotherhood, a small fist, covertly ask around and soon enough you will find a member.
The secret phrase is "under the stars" the response "The moon shines the brightest"