Kurse all SeeD. Swarming like lokusts akross generations. You disgust me.
There are multiple different theories as to why Ultimecia is attempting to compress time, among them the Lone Wolf theory; the Goddess theory; the Power theory; and the Wicked theory. There are other theories, as well: some fans believe that Ultimecia is simply trying to compress time because she is innately evil or totally insane; others believe that Ultimecia is actually a grief-stricken Rinoa from the future. However, the former theory gives Ultimecia no background, while the latter has been declared false by the Final Fantasy VIII Ultimania guide itself.
The Lone Wolf theoryEdit
The Lone Wolf theory is based on the fact that a Sorceress has human lifespan and is not immortal. By compressing time with herself in the center, Ultimecia would become a immortal being, retaining her life and youth for eternity, alone in one everlasting moment. The fact that she knew that she was destined to be killed by SeeD furthered her intent, and she attempted to use Seifer and Edea to exterminate SeeD before they could fulfill their part in her demise.
Although this theory fits the story of Final Fantasy VIII, it also assumes that Ultimecia would actually want to be left alone in a void of nothingness, literally forever. It is possible, of course, that she would, but considering her apparent enjoyment of publicity and festivity, this seems unlikely.
The Goddess theoryEdit
The Goddess theory centers around the information given if Ultimecia is Scanned during the final battle with her:
"Ultimecia, transformed to absorb all time and space. Absorbing all existence as we speak."
If Ultimecia could absorb all of time and space as we know it, it is perfectly possible that she could use her Sorceress Power to recreate the universe according to her own wishes, with herself as the Creatrix, ruling over everything in existence.
This theory also fits the story of Final Fantasy VIII, but Ultimecia demonstrates few power-hungry tendencies throughout the game. She becomes ruler of Galbadia while controlling Edea, but only to further her plans for destroying SeeD; furthermore, while giving her speech to Galbadia, the fact of her taking power as the "new ruler" takes a backseat to the idea that the people she is speaking to are (in her mind, at least) filthy, detestable hypocrites. Thus, although the Goddess theory makes sense with the story (and fits the tradition of the Final Fantasy villain) it does not make sense with Ultimecia herself.
The Power theoryEdit
The Power theory stems from the evidence shown within the game that the Sorceress Power definitely has a visible physical effect on those who receive it. The veins on Edea's face; Adel's superhuman physique; Ultimecia's wings; the appearances of the Sorceresses in the Commencement Room. With the exception of Rinoa, who has not had her Power for very long, all of the Sorceresses in the game display some sort of physical mutation. The basis for the Power theory is that the Sorceress Power corrupts the mind as it does the body - this would serve as a partial explanation for Adel's tyranny, and if it were true, then Ultimecia's mind would be damaged beyond repair. Further credibility is given to this theory by Ultimecia's final form; this massive, repulsive figure has a pale-skinned, silver-haired woman hanging, helpless and inverted, beneath the folds of its trailing robes. This pitiable figure might in fact be the true Ultimecia, so long steeped in her rage and hatred that her Sorceress Power has actually taken over her entire body.
The major problem with the Power theory is that the idea of Sorceress Powers being able to influence a person's personality is a pretty important fact to leave out, and there is certainly no textual evidence throughout all of Final Fantasy VIII to support it. As a result, although the Power theory cannot really be disproven, it can hardly be proven, either.
The Prophecy theoryEdit
The Prophecy theory is named as such due to the theory that Ultimecia's rise to power and her defeat by SeeD was a self-fulfilling prophecy. Due to her actions in the past, by the time Ultimecia was born in the future, discrimination against Sorceresses due to the actions to Adel, Edea and her future self in the past would have only increased. The young Ultimecia would have been prosecuted and hated for actions she hadn't even committed yet. The theory goes that, twisted by and resentful of this injustice against her, Ultimecia would effectively seek to defy fate and not only fulfill the preordained events, but perhaps change them and alter the time loop so that, in the end, she somehow emerges victorious. In essence, the theory states that Ultimecia is already aware of her fate to be defeated, and goes along with the preordained events to change that fate.
It would make perfect sense that Ultimecia would know of her eventual fate, seeing as it occurred in the past and has doubtlessly been added to the history books as one of the greatest battles of all time. However, regardless of how logical this conjecture is, it still remains conjecture; there is no proof of this theory throughout Final Fantasy VIII, although it does at least seem to correspond with the little canon information we do know in regards to Ultimecia.