"You've been planning this from the beginning."

 One might say that Jack Sparrow and Will Turner have had a rocky past. It started with a duel, Which Jack won I might add. And it was all downhill from there. Jack and Will formed a partnership and went off to rescue Will's secret love Elizabeth Swann. Now this might seem wonderful and friendly so far, but just wait! They found dear Lizzie and then dumb Will got her and Jack marooned on an island. Jack and miss Damsel in Distress were then rescued by Norrington, Elizabeth's almost fiance. While on board Norrington's ship

Elizabeth tries and fails to convince Norrington and her father the Governor of Port Royal that they have to go and find The Black Pearl  to rescue her beloved Will. If at first you don't succeed try try again they say.  And try she did. In the end she had to promise her hand in marriage to our favorite naval officer James Norrington.  So the ship set sail yet again in search of Will. 
 
Upon arrival Jack had a nice heart to heart with Norrington, he laid out a perfect plan for Norrington (which he later ignored) and then convinced James to allow him to enter the island and negotiate with the Pirates. As soon as he arrived on Isla de Muerta Jack was putting his plan into action. When he was "captured
by Hector Barbossa Jack laid it all on the table. He puts Will's life on the line but he was trying to help the pirates really he was!: Hector: "I suppose in exchange, you want me not to kill the whelp." Jack: "No, no, no. Not at all. By all means, kill the whelp. Just not yet. Wait to lift the curse until the opportune moment. For instance...After you've killed Norrington's men. Every last one."[Jack steals an Aztec gold coin] Will:"You've been planning this from the beginning. Ever since you learned my name."Jack: "Well...Yeah."   Why does Will's name matter? Well the cursed crew of the Black Pearl needs Will's blood to de-curseify them. Now if Norrington had listened to Jack they would've been saved from the onslaught of invincible pirates. But Norrington is a bit prideful and didn't use Jack's plan.  Hopefully He and Elizabeth will live to fight another day...Oh wait Elizabeth escaped the watchful eye of the officer's and rowed to the island to join in the excitement during the pirate attack. Possibly her smartest move ever.
She quickly reunites with Will. Jack is off fighting Barbossa and doing quite well until Barbossa strikes what he thought was the killing blow, just then Jack stepped into the moonlight and shows his little secret, he too is cursed. Remember that coin Jack stole from the chest earlier, Well because of that little theft Jack became cursed like the rest of the crew. So the fight could go on forever. Lucky for Jack he has Will in his corner and whenever Jack chooses to end it he can just drip some blood in the chest, and it will all be over. IF Jack ever wants to end it that is...