Worst Final Fantasy characters?

[Mr. Carnelian]

I really dislike X Yuna and XIII Serah.

FFX Yuna: like Wolf pointed out, she's a total doormat. And for most of the story, she's so irritatingly passive - take charge, woman, you're the one with the awesome summoning power!

FFXIII Serah: she's stupid, she's marrying an older man - who she's only just met, really - at the age of 18, and her only real purpose in the story is to be a damsel in distress.

However, both of them get a lot better in their sequels, X-2 and XIII-2. They both grow some backbone, and become more independent and assertive.