In FFVII, Seifer Almasy is mentally seduced by Edea to become her knight; her right hands in almost everything she does. The concept of the Sorceress’s night is often times confused, even by Seifer himself. But, the bottom line is, they are the protector of the sorceress at any cost.
So is this a romantic sense? Seifer often commented that it was his romantic dream to be the sorceress’ knight, but his relationship with Edea and Ultimecia was far from romantic. The Knight serves as less of a lover and more of a friend; one of the few people that are close to her and can keep her from loosing her human qualities [which, as we saw with corrupt sorceresses like Adel and Ultimecia, leads to horrible things.]. There is also, of course, the fact that this one man does all of the sorceress’s bidding and is somewhat of a consort to her power.
So why would Ultimecia want a knight, when she was [probably] knight-less in her own time? Seifer was more of a pawn in her plan than anything, and she knew that she could get him under her control and use his knowledge [and strength] to her benefit. It is hard to say whether or not Seifer did all the things he did out of his own will, or purely because he was being controlled on every level, but we do know is that his role was less than that of a true knight.
Edea’s knight is, of course, her husband Cid. She lived for [at least] 10 years with Ultimecia’s power and did not let it take her over. You could speculate that her knowing the future from Squall helped her keep control of herself until she was truly possessed, but even prior to the possession Edea was a candidate. Her own willpower, combined with motivation to save the future world and a loving and supportive husband by her side kept her sane.
In the case of Rinoa this concept is a little different. Her and Squall loved each other deeply, but as the story progressed after her receiving her powers, she seemed to be lost and helpless and trying to figure herself out, slowly growing more and more apart from her beloved. Squall’s ambitions to keep her alive, save her from those that captured her, and [essentially] be with her kept her from getting lost in time compression, to Ultimecia’s possession, and in her own sorrow. Truly the definition of the sorceress’s knight.
For the Ultimecia = Rinoa theory lovers, this can carry over into her character. It is said that sorceresses can live much longer than regular humans, and the only time that they either die or can die in peace is when they relinquish their powers. Adel seems to be an [almost] good example of this; she has been around for some time, determined to leave her crypt suspended in space and, once released, still pretty much has her full magic potential and does not seem to have aged one bit. Even Edea, who could be anywhere from 30 to 40 in the game does not seem as aged as her husband, Cid. With that, the idea of Ultimecia being Rinoa’s future self, filled with hatred and a desire to destroy SeeD, her castle placed in the exact location Rinoa and Squall plighted their troth, with the Guardian Force exactly the same as Squall’s ring, and lacking the true knowledge of SeeD, she seems to be a likely candidate. [But only a theory and nothing more]
Ultimecia’s lack of a knight [and, if she is in fact Rinoa, Squall] lead her to lose what inside of her was human and do nothing but destroy the world and whatever it was that took Squall/her Knight away from her.
So, while these tales of great and evil sorceresses and their knights are nothing but legends and mythologies in the world of Final Fantasy 8, they have their importance in what really goes on within the lives of those affected by the sorceress.
