Captain Jack Sparrow is an inconsistent friend of the party, keeping them constantly on their toes as whether or not to trust him or not. He has often stolen from them, but has also volunteered to transport them on his ship (for a price of course).
During Perils in Pirate Province, Jack revealed that he is the Pirate King of the Sian Republic. Although leaning on the side of the Calicans, he has not pledged his help yet, hoping a deal could be struck. For the hand of Diamond Lil the army could have the help of his pirate army. So far he has not been successful with his demands.