The Curse of the Black Pearl

James Norrington (Portrayed by Jack Davenport)
When we first see James in The Curse of the Black Pearl, he is on a ship with Elizabeth Swann (who is a child), her father, and Joshamee Gibbs. James is a lieutenant (probably First Lieutenant), and feels very confident in his assumption that pirates deserve "a short drop and a sudden stop". But really, give him a chance, he gets to be very lovable. Cuddly, even, for a Commodore. Okay, that's a totally biased exaggeration, but hey! Jack roots for him!

Captain Jack Sparrow (Portrayed by Johnny Depp)
Captain Jack Sparrow, whom we will always remember as... well, something Captain Jack Sparrow'ish. He, in a sinking ship, arrives in Port Royal (where the action kicks off) proceeds to bribe the port master fellow, and then promptly pilfers a pouch of money. As we go along, we find he's really an exceptional pirate, and had his Black Pearl stolen from him by mutinous dogs (not really dogs, so much as about-to-be-undead pirates). He's also quite the tramp, has been to Singapore, and burning his supply of rum will make him quite irate. And he is honest about his dishonesty. Honestly.

Will Turner (Portrayed by Orlando Bloom)
When we first meet William Turner, he is quite young, and is floating, unconscious, on a makeshift raft alongside the same ship where we first see Norrington, Elizabeth, et cetera. Once brought on board, Elizabeth discovers that he has a medallion around his neck, which could indicate that he's a pirate, so she takes it to prevent such identification. Will grows up and is a blacksmith, secretly fashioning swords that are both practical and aesthetically pleasing. Because he loathes pirates, he practices with those swords three hours a day (to which Jack says "you need to get yourself a girl, mate"). When Elizabeth is taken by Barbossa and his crew (because she had the medallion), Will enlists Jack's help in rescuing her.

The Trio
In TCotBP, Norrington is the stalwart military man, upholding the honor and integrity of the British Navy, Will is a sometimes naive do-gooder, and Jack is a pirate. All of their clashing personalities serve to make them not so trusting of one another, nor very forgiving at times. What bonds their adventures together, however, is the lovely Ms. Swann. Norrington wants to marry her to make his suitable life even more suitable, Will is in love with her and would die for her, and Jack mostly thinks "I'd tap that" or "you're rather handy".
At the end of TCotBP, Jack is to be hanged, and Elizabeth is to marry Norrington, but then! Hark! Will, in a very fine hat, shows up and rescues Jack from the gallows. They make a break for it, make it a good... well, several meters, before the marines catch them. Norrington is brandishing his sword at Will and Jack, Jack rather hiding behind Will. Norrington says, "You forget your place, Turner." And Will says, "It's right here, between you and Jack." Which... yes, please!
Ahem, anyway, and then Elizabeth moves to stand beside Will and says, "As is mine." And Norrington is crestfallen, poor fellow. Then Jack sees Mr. Cotton's parrot, and decides it's all right if the attention is on him again and wields both adverbs and his own concept of personal space, before deliberately jumping falling off the side of the fort and into the sea and swims toward his beloved Pearl. Commodore Norrington thinks they "can afford to give him one day's headstart".

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