Mercenaries, thieves, lords, and a banker round out the neutral parties in the War of the Five Kings. They're an eclectic bunch with but one thing in common: service to the most deserving party.
Lord Walder Frey's shifting loyalties are well known, while the sellswords Bronn and Daario Naharis will pledge their blade to the highest bidder. Brienne of Tarth cannot be bought, but has battled alongside nearly every faction while the thief Jaqen H'ghar will serve only himself. Vargo Hoat's vile company will happily kill for coin, and it could be argued that Tycho Nestoris of the Iron Bank of Braavos will do the same.