You are correct. She isn't written very well but then they made the mistake of casting the awful Penelope cruz. Big mistake.

I don't think she's any less credible than Knightley or Bloom on that score. I think there is some sort of bias against her because she's not playing a sympathetic, heroine. She's playing an ex who has every right to be ticked off. She's obviously seeking the love she hasn't been able to find (Jack ditched her) and she now wants the love of her father, no matter who he is. Jack revealing that her own father doesn't care if she dies, doesn't make her any happier with herself as well as Jack. If not for him, she could still be living the lie or dying by it. For her, being betrayed by Jack twice is just too much.

when she commanded the line "steady as she goes", sounded like she was just saying words that she didn't know what that meant. It's kind of amusing if you ever find yourself watching her in that scene.
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The character was not meant to be loveable. She's ticked off and why not? Her father is a killer, her boyfriend left her flat (allegedly after deflowering her) and all she wants is someone stable in her life. She's not hard to understand. She didn't see Jack killing her father as being saved. She saw it as an act of viciousness because she didn't get the opportunity to have the father she wanted and "save his soul".

I thought she was a great companion to Jack. Not someone he'd ever settle down with, but someone to come in and out of his life.
She hates being beholden to him, but I do not think she hates him. I think she loves him in her own way, but knows it can't go anywhere. Neither of them is the settling down type, after all. But "what if" probably crosses her mind occasionally.

and I don't think she had much chemistry with Jack.
That's the key point. Neither of them actually seemed to want to be around the other unless there was something to be gained, so yeah, you don't end up caring a lot about her, because Jack doesn't seem to.

I loved her! I hope she comes back for part 5. She doesn't hate Jack, she's just angry with him, but I don't think she hates him.

I dunno about "EXTREMELY annoying", but yeah I didn't like her that much either. She just wasn't a very likable character, and I don't think she had much chemistry with Jack.
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