Explanation on the R=U theory?

[Sir Bahamut]

though I have to say I've become less impressed by the Japanese text this time around. I remember it being more conclusive that Griever was summoned from Squall. In the quotations you posted, it seems at least fairly ambiguous what she is actually referring to. It also wasn't important enough to be retained in the translation.

Um, how is that ambiguous? Look at it again:

Ultimecia: Your feelings, I shall summon the most powerful of things
[from them]! The more strongly you feel, that will be what shall torment
you. Fufu."

She says to Squall that she will summon the strongest thing from his feelings, and that the more strongly he feels, the stronger the summoned thing will be. She then proceeds to summon Griever. Where exactly is the ambiguity?

I still just don't see Griever as Squall's greatest fear.

I never said he was either. I said Squall considers Griever to be the strongest creature. I agree that Squall probably doesn't have nightmares about Griever, but he makes it clear what he thinks of him:

Squall: "It's not a monster. It's a lion. Lions are known for their
great strength and pride."

Although he doesn't explicitly say that Griever is the strongest creature ever, this background information is enough to justify Ultimecia's summoning of him.

As for the translation, it is implied (vaguely I'll admit) in the scan info that Griever is from Squalls mind, as it says "In Squall's mind, the strongest GF", but really it doesn't matter what the translation did and did not edit. The fact is that the japanese version is necessarily going to be closer to the truth.

Apart from Ultimania, I have yet to see anything which convinces me R=U is even close to impossible or even very unlikely. You can infer how a random individual could have become Ultimecia, but that seems a lot less interesting, and far less involved in the 'fate' theme running through the story.

It certainly isn't "impossible", because anything is strictly speaking possible. The only problem is that it isn't actually implied by the game to be true to begin with, which is why it IS unlikely. You agreed yourself that the hints for the theory come from backwards reasoning, which is enough in itself to demonstrate why the theory is unlikely to be true. If it isn't suggested by the game, it cannot be considered a valid theory. It's that simple.

As for the theme of fate, the game itself readily implies a background for Ultimecia which links strongly into the theme of fate. That is, that Ultimecia was persecuted before doing anything because her fate was known to the public (she died in the past, remember, so she would have been as known to the FF8 world as say Hitler is to us), and in an attempt not only to get revenge on the people, but also to avoid her own supposed fate of dying at Squalls hand, she tries to inititate time compression, thus setting in motion the events that lead to her death. Perfectly fits in with fate, is implied by the game AND the Ultimania and doesn't require any baseless assumptions about Ultimecia really being a main character. It just doesn't make sense to try looking for technicalities that can allow R=U to work when it isn't really backed up by the game and the game itself offers a perfectly reasonable background to begin with!

The expanded theory described above can be read in the FAQ referred to.

I have never suggested Rinoa travelling to the future, all R=U theories I know of work around her surviving to the future (hence the problem posed by Ultimania). The time travel I was referring to was in fact TC. Squall and co. go to 'the future' and meet someone, storywise it isn't that strange that they should have met them (or a relation) before.

If you never meant to imply that Rinoa travels to the future I'm afraid I fail to see how the fact that timetravelling occurs in the game somehow makes R=U more plausible.

EDIT: Oh, and the Ultimania explicitly states that sorceressess have human lifespan, so it is impossible for Rinoa to be Ultimecia unless some necessarily baseless assumptions are made. Arguments such as Edea looking young don't mean anything against the Ultimania I'm afraid...