Jadzia indeed seemed to possess a quiet self-confidence in early episodes (her interactions with Bashir certainly stressed that aspect of her personality, in contrast to his bumblings). Even in episodes like "Dax", where she was put through the wringer and had to confront the ghosts of past hosts (not yet in the literal "Facets" way

), she seemed quite self-possessed albeit in a reserved fashion. Then in season two she seemed to become quite insecure in many ways. I blame Verad, personally. I like to think season one Jadzia Dax was a successful joining of a quiet, studious woman who occasionally pushed herself too hard with a sly old symbiont which allowed her a wry perspective and a ease of being that complemented her intelligence to provide a "wisdom". Then Verad messed up the equilibrium and season two Jadzia struggled a bit to find it again- and repeated intrusions by past host matters (e.g. the Blood Oath) saw her embracing more of her older hosts and less the "Jadzia" personality. Then in early season three Joran makes himself known, and she learns to embrace those repressed memories...then in late season three she confronts the repressed Curzon-loved-Jadzia memories and learns to embrace Curzon....and eventually Jadzia Dax settles into an equilibrium again, but this one different from her earlier balance, more excitable, more "flirty", more dangerous, more Curzon-with-a-bit-of-Joran. She becomes Klingon Party Girl!

And thus she remains until death.
That's my theory, because while I liked Jadzia Dax in all her appearances, she did shift a bit in character. I think, though, that it does all make sense.
I totally agree with you
Nasat! To me Jadzia's shifts in personality made perfect sense, I think her personality during Season 1 was probably the closest to what she was like pre-joining, and as each year progressed (and the aforementioned events occured) she learned to integrate those parts into herself, and changed as a result.
EXACTLY--she turned into a female Curzon. And I think that THIS is actually at the root of Ezri's fear of losing herself, not just the suddenness of the joining...Jadzia lost herself to the memories of Curzon and Ezri is fighting it.
I dunno if I completely agree with this interpretation
Nerys, though I think we've probably discussed this in the past... But I've never thought of Jadzia as a female Curzon - I think the main reason we tend to jump to that conclusion is because he is the host we learn the most about.
I will agree that his memories made a strong impression on Dax, though perhaps that has more to do with the fact that he was a host to Dax for many decades (was he joined the longest?) and also because he was the most recent host.
But I don't really think that Jadzia
completely lost herself to the memories of Curzon -
Nasat's explanation makes the most sense to me.
As for Ezri, we only saw her for one season, where she was very much struggling to figure out who she now was. If all we saw of Jadzia was season one, then our interpretation of her would be completely different. I personally believe that, had the show continued, Ezri would also have gradually changed as she embraced all the past hosts and learned who Ezri Dax (as opposed to Ezri Tigan) was.
But I've managed to completely tangent in my own thread, oh the irony!
I would really have liked to see something based around that. It would have to have a little more plot depth than just having Jadzia without Dax around, quite possibly a situation like the one TerokNor described above.
In fact, an episode based on this concept would have been better than half the Jadzia episodes we got.
The unjoined Jadzia we saw briefly in Invasive Procedures seemed insecure, but obviously that was because of circumstances. It's hard to know what she was really like without seeing her in a normal situation.
Now don't get me wrong, I loved Jadzia episodes because I think Dax is the most fascinating Star Trek character. But I think, in addition to the episodes we got, we should have learned what Jadzia was like pre-Dax.
And as you said, its hard to know whether what we saw of her in season 1, and in Invasive Procedures, was what pre-joined Jadzia was like in a normal situation.
Some possible scenarios for a Jadzia-centric episode include -
A parallel universe (perhaps similar to the TNG episode "Parallels") where Jadzia switches with an alternate version of herself, who would then be on DS9 with our regular crew. She may or may not still be a Starfleet science officer, perhaps she's a visiting Trill scientist instead.
A 'time travel' episode (maybe similar to "Wrongs Darker than Death or Night") where Jadzia or one of the main crew goes back in time to witness an event which shaped pre-joined Jadzia's life.
Or as suggested by
Kathryn-janeway, they could have visited Jadzia's family (similar to "Prodigal Daughter") - she mentions having a sister who isn't joined, maybe something could have happened with her.
I think it was a definitely a mistake on the writer's part to focus solely on Dax, it seems every episode that featured Jadzia focused on Dax, and because of that we learned next to nothing about Jadzia's family, backstory or interests prior to joining.