Well, I'll explain the theory & will add some extra details. Don't think I've added everything, but here goes:
The theory is that during the development process of FF8, Rinoa was originally Selphie (SeeD) or vice versa. Plot wise.
For whatever reason, when SquareSoft created new characters (especially Selphie and Irvine), they changed thier mind and just separated / split Rinoa into two different characters all in the name of the plot (into Rinoa and Selphie.) Selphie became the SeeD, instead of Rinoa.
Yes, the current game tells us that it's quite unlikely for Rinoa and Selphie to be the exact same person. However the game shows us that the two characters have certain similarities and qualities to each other (excluding the first demo though as that's not canon but I'll show it anyways).
Consider:
1)
There are two different demos of VIII. You can look for more info here:
http://finalfantasy.wikia.com/wiki/F...tasy_VIII_Demo
In the trial version (the first demo, both in Japanese and English), Rinoa was there instead of Selphie. Rinoa herself was eventually replaced with Selphie in the newer demo version / retail version.
The first trailer of VIII (or second, whatever) in Japanese:
https://www.youtube.com/watch?v=DxnzNVIAxCY
I don't know the exact date of this trailer and the japanese demo, but they were definitely middle somewhere in 1998.
The final Japanese game was released on February 11, 1999 and the first demo (in English) released some months later. I'm guessing that SquareSoft used the Japanese demo for translating work (saves time and effort) instead of re-using the finished Dollet portion from the final Japanese game as that'll take more time and more effort, I think.
I've also found some old articles regarding the development of VIII, but it's on IGN. Example:
October 30, 1998 -
Sit up and take notice, Final Fantasy fans. Square has revealed two new characters from the game we're all waiting for.
Irvine Kinneas, a cowboy gunslinger with a ponytail, is joined by a young chain-wielding woman named Selphie Tilmitt. Both characters evidently appear later in the game, and both can join your party and partake in combat.
Source: http://ign.com/articles/1998/10/31/m...cters-revealed
And
August 26, 1998
Previously, the game's female lead, Rinoa, was the only character believed to possess the ability to summon creatures into combat ¿ namely Leviathan. Given this latest revelation, the idea of FFVIII's hero, Squall Leonhart, having his own Guardian Force appears more likely than ever. We'll keep you posted.
http://uk.ign.com/articles/1998/08/2...ares-new-force
Look at the dates. Characters like Squall, Rinoa, Zell, etc. were probably announced earlier. IGN won't show any older article than 1998/08/27, sorry but if the articles above are accurate. It suggests that SquareSoft didn't initially think of Selphie and how would that impact the story / plot relating to Rinoa.
Now, I just want to add more info regarding the differences between the demos.
Take a look at the Dollet mission in the retail version:
Selphie running away from X-ATM092. Notice her Sun shadow? That's Rinoa's shadow from the trial version.
Inside the vision of X-ATM092, you can clearly see Rinoa instead of Selphie:
Now, when you load the Trial version (or the very first demo, whichever fits), this screen shows up:
This basically tells you that, the special team of SeeD (also candidates) is dispatched to Dollet to fight the war. This team consisted of Squall, Zell, Seifer and Rinoa.
In this whole trial version, Rinoa has no dialogues. All she did was laugh when a dog was licking Seifer's leg and when you talk to her, she always say "...". On the other hand, Seifer, Squall, Zell and Dollet Solider (Selphie) all had dialogues. Also, at the end (running scene), Quistis wasn't there, it was just another soldier using the machine gun.
After the boss fight at the communication tower in Dollet, Rinoa disappears and then Dollet Solider (Selphie) appeared. I imagine that this is because if Rinoa didn't disappear, the game would have crashed due to conflict of game code.
That Dollet Solider is future-to-be Selphie.
Now, let's compare the dialogues (after the boss) from trial and retail versions:
Trial version:
Code:
Dollet Soldier: "Are you from the B squad?"
Squall: "I'm...Squall from B squad."
Dollet Soldier: "Who's the squad leader?"
*Squall's gesture*
Dollet Soldier: "SeeD and SeeD trainees are to withdraw at 1900 hours. You are to assemble by the shore!"
Seifer: "Withdraw?"
Dollet Soldier: "I only came here to deliver this message..."
Dollet Soldier: "and I'm sure you can appreciate that this withdraw is a direct order!"
Seifer: "@#$%..."
Seifer: "What time do we meet?"
Dollet Soldier: "As I said, SeeD and SeeD trainees are to withdraw at 1900 hours. You are to assemble by the shore!"
Seifer: "1900 hours... that's in only 15 minutes!"
Seifer: "15 minutes... Come on!"
[Seifer takes the elevator down.]
Zell: "Wait!"
Zell: "Off on his own again!"
Zell: "He's selfish... I don't like him!"
*end script, taking the elevator down is the next step*
Retail version:
Code:
Selphie: "Squad B Captain? S'cuse me! I have new orders! All SeeD members and SeeD candidates are to withdraw at 1900 hours. Assemble at the [shore]!"
Seifer: "Withdraw!? There are still enemies around!"
Selphie: "I know, but I'm just a messenger."
Squall: "An order to withdraw takes priority. I don't want to miss the vessel."
Seifer: "What time d'you say?"
Selphie: "Like I said...! All SeeD members and SeeD candidates are to withdraw at 1900 hours. Assemble at the [shore]!"
Seifer: "1900 hours...We only have 30 minutes! You got 30 minutes to get down to the [shore]! Better run!"
[Seifer takes the elevator down.]
Selphie: "Heeey! Wait for us!"
Zell: "Who the hell does he think he is!"
Squall: "Why don't you ask him. Let's go."
*end script, taking the elevator down is the next step*
You can watch the first demo on YouTube here:
https://www.youtube.com/watch?v=d4Htw3YRTkU
Remember that this is the very first demo. The second demo is changed. This second demo is exactly the same as the Dollet mission from the retail game (final version). This trial version is just like an "Alpha" release where things will be most likely changed in a later release.
I don't buy for a second that SE had added Rinoa in the first demo just to stoke our hype because of three reasons:
a) Why would Rinoa be any of interest to us when she literally had no dialogues (she always said "...") in this first demo? Last time I played it when it came out after FF7, I wasn't interested in Rinoa... I was more interested in the new gameplay mechanism. I'm sure most people had felt the same back then.
b) There's a lot of major differences in between the first demo & the second demo. Why go all that trouble to change a lot of things? Dollet soliders transforming into characters, new / added / changed dialogues, some gameplay mechanisms, characters' redesigns, music, etc. Also, look at the dates of the articles -- which strongly impiles that Selphie wasn't created at the same time as the other characters (Squall, etc.)
c) The Trial version shows you a brief mission (the special team of SeeD...), so we read it and we acknowledged Rinoa as a SeeD (or candidate) at the time. But most importantly, there's nothing in the version that states "major plot / characters may be subject to change..."
Because of the three reasons above, it's strongly suggested that SquareSoft had a different plot outlook when they were still making the game.
2)
Rinoa and Selphie were only the two characters that asked Squall for a tour of the Balamb Garden. Re-using / re-cyling stuff in game development is very common, sure, but we are talking about Rinoa / Selphie here.
3)
Selphie's "THE END" limit break. You can watch the limit break here:
https://www.youtube.com/watch?v=WfCEGx8HeYc
(starts at 01:00)
This limit break strongly resembles to Rinoa's moments when she was out in the green field with floating flowers during certain FMV(s). The text "The End" seemed fitting because Rinoa was again out in the same field at the ending. It's like a metaphor... that everything is about to end and live happily afterward. It's also the same place (or similar) where Squall and Rinoa *promised* to meet. As shown / displayed in the first cinematic scene (I'll be here....) and at the Matron house later into the game (late Disc 3). Yet, this "The End" limit break belongs to Selphie.
Also, there's just something odd about the core of Selphie's limit ability.
Selphie can use NORMAL / SPECIAL magic from her limit break without junctioning any GF and without any DRAWN magic.
Rinoa can't even use her limit break (Angel Wing) if she has no magic junctioned.
4)
Personality wise, Selphie's traits are pretty simple (emphasis on happiness-crazy, craziness and explosive-alike) whereas Rinoa's traits are more complex (nothing crazy or explosive a-like, though). In other words, Selphie is a person who doesn't care about consequences due to her sociopathic behaviour, but Rinoa is totally the opposite (caring, sweet, etc.) and she actually worries about the consequences.
Also, in Selphie's diary on the Balamb computer, she says "I think Rinoa and I are a lot alike." which is way out of character.
This is pointless, but if we add Selphie's traits to the whole R=U equation, well that would make the R=U theory itself a lil more "plausible" but forget about that for now.
5)
We were given premission by Cid to read Selphie's diary on the personal computer and we did so. Selphie didn't mind at all. BUT when Squall switches on the computer in Trabia Garden and Selphie's Personal Data bank (info, diary, I guess) shows up, then Selphie came quickly and corrupts the computer, so we can no longer read her data; showing that she didn't want us to see her Trabia data.
That Trabia scene doesn't literally make sense to me at all.
If Selphie was willing to say something crazy (her dialogues) or not caring about what other people think AND willing to share her diary / her opinions and feelings on the Balamb computer for all to see, then why would she do the opposite thing in Trabia? Why would anybody else in Trabia be upset / whatever if they read her data?
Now, if she was Rinoa, that would make a lot more sense since Rinoa had a lot of things / issues that are maybe better left alone. Because many times she says that she doesn't want to *embarrass* everybody, that she doesn't want everybody to get the "wrong idea", that she wants to support the team, that she obviously loves Squall, etc. If she expressed all that feeling into a computer, then her action would make a lot more sense (not allowing anybody to see it) like in the Trabia scene.
Why SquareSoft changed thier mind and messed up something (or not?), your guess is as good as mine.