If you want to do some quest writing, there are (at least) two openings. "Devlin Opera" has been unfinished for a long time. Or, for something smaller to get you started, have you tried playing the "Help the Lady" sidequest? That's the one in which you meet Armand Delacroix, meaning you get to try out his new dialog. It ends with him telling you to look for a letter back at the Pirate Settlement, presumably leading to another quest with Armand and Estrella - but at present there is no letter and no follow-up quest...
I'd advise not making sweeping changes to the "standard" storyline. It's the original PoTC game storyline and is still recognisable. Being something of a traditionalist, I for one would rather like it to stay that way. But apparently the original game writers wanted to make it playable as Danielle, so making the dialog use placeholders and having the main NPC change to Nathaniel Hawk if you're female would fit in well.
You could also try copying an existing sidequest. Change names and locations, change dialogs to make your version more distinct, and go on from there. (Ever talked to Rys Bloom? Ever talked to Fred Bob? Rather similar, aren't they? )
I'd advise not making sweeping changes to the "standard" storyline. It's the original PoTC game storyline and is still recognisable. Being something of a traditionalist, I for one would rather like it to stay that way. But apparently the original game writers wanted to make it playable as Danielle, so making the dialog use placeholders and having the main NPC change to Nathaniel Hawk if you're female would fit in well.
You could also try copying an existing sidequest. Change names and locations, change dialogs to make your version more distinct, and go on from there. (Ever talked to Rys Bloom? Ever talked to Fred Bob? Rather similar, aren't they? )