Canons are not interchangable. D:
So, you wanna write about the FF characters/put in FF characters who didn't appear in KH in your fic, right? That sounds dandy! But there are a few things to remember...
Kingdom Hearts can be called two things, if you ask me. One is a crossover of epic proportions. The other is an alternate universe story. Every single Final Fantasy character and most, if not all, of the Disney characters have different backgrounds, whether the changes are minor (Such as Simba, despite the events if the Lion King movie not happening yet, knows Sora due to being summon) or major. (Tidus, Selphie, and Wakka are young teens living on Destiny Islands) This means you have to adjust the characters and their relationships more appropriately.
The best example to use here is Leon, since he's had so many changes. First of all, he's much older than his Final Fantasy VIII incarnation. When Radiant Garden fell to the Heartless, he was sixteen. In KH, it was said he and the others have been living in Traverse Town for nine years, making him twenty-five at the start of the story. Personality wise, he's different, too. FFVIII!Squall was hesitant to take leadership, and it was forced upon him. Leon willingly takes on those responsibilities, and is much more mature and at least a bit more friendly and sociable than his counterpart. He still maintains some of that grouchiness from orignal canon, but he has been changed to fit the setting of Kingdom Hearts much better.
Now let's say you want to put Rinoa in your Kingdom Hearts fic. It's not so easy as just plopping her in there. There will have to be adjustments to things you'll have to make.
You could put in Rinoa from the world of Final Fantasy VIII - however, Leon won't recognize her and just get angry and confused if she starts calling him Squall. He'd be wary of her, maybe even think she's an agent of Maleficent and/or Organization XIII for knowing his real name, which no one outside of the Radiant Garden residents or people who found out some other way (Like Sora) should know. That's because Leon has an altered background. He has no idea what Balamb Garden, SeeD, or the FFVIII concept of Sorceresses and Sorceress Knights are. He does not know who she, Zell, Irving, Quistis, Selphie or Seifer (both the FFVIII and KH versions of Selphie and Seifer) are.
...actually, I'd love to see a fic like that. A realistic FFVIII Rinoa and Leon meet and drama comes from misunderstandings. FFVIII Rinoa meets a "new" Squall and adjusted her life to him. He may or may not live up to the Squall she knew before, but she eventually accepted him as a different person, or she can struggle to try to make him the Squall she knew or keeps forgetting he's not her Squall and mistakenly treats him that way.
Another thing you could do is put Rinoa in, knowing who Leon is and Leon knowing her and all that. But you'll have to give her an altered background. You could write her as someone who lived with the rest of the Final Fantasy cast in Radiant Garden, or you could make her someone he met in Traverse Town. Or make her a spectator in the Olympus Coliseum who was amazed at the way he fights. Be creative!
This doesn't just apply to Rinoa, but to any other FF canon character with relations to the KH FF characters you may want to put in, whether it's Celes, Zidane, or Seymour. It's tough to do and requires lots of planning, but it can be done. I've seen too many fics that take the easy route and just follow FF canon when KH canon should trump. Then you're not writing a KH story. You're writing a FF story that uses KH's setting.
Kingdom Hearts can be called two things, if you ask me. One is a crossover of epic proportions. The other is an alternate universe story. Every single Final Fantasy character and most, if not all, of the Disney characters have different backgrounds, whether the changes are minor (Such as Simba, despite the events if the Lion King movie not happening yet, knows Sora due to being summon) or major. (Tidus, Selphie, and Wakka are young teens living on Destiny Islands) This means you have to adjust the characters and their relationships more appropriately.
The best example to use here is Leon, since he's had so many changes. First of all, he's much older than his Final Fantasy VIII incarnation. When Radiant Garden fell to the Heartless, he was sixteen. In KH, it was said he and the others have been living in Traverse Town for nine years, making him twenty-five at the start of the story. Personality wise, he's different, too. FFVIII!Squall was hesitant to take leadership, and it was forced upon him. Leon willingly takes on those responsibilities, and is much more mature and at least a bit more friendly and sociable than his counterpart. He still maintains some of that grouchiness from orignal canon, but he has been changed to fit the setting of Kingdom Hearts much better.
Now let's say you want to put Rinoa in your Kingdom Hearts fic. It's not so easy as just plopping her in there. There will have to be adjustments to things you'll have to make.
You could put in Rinoa from the world of Final Fantasy VIII - however, Leon won't recognize her and just get angry and confused if she starts calling him Squall. He'd be wary of her, maybe even think she's an agent of Maleficent and/or Organization XIII for knowing his real name, which no one outside of the Radiant Garden residents or people who found out some other way (Like Sora) should know. That's because Leon has an altered background. He has no idea what Balamb Garden, SeeD, or the FFVIII concept of Sorceresses and Sorceress Knights are. He does not know who she, Zell, Irving, Quistis, Selphie or Seifer (both the FFVIII and KH versions of Selphie and Seifer) are.
...actually, I'd love to see a fic like that. A realistic FFVIII Rinoa and Leon meet and drama comes from misunderstandings. FFVIII Rinoa meets a "new" Squall and adjusted her life to him. He may or may not live up to the Squall she knew before, but she eventually accepted him as a different person, or she can struggle to try to make him the Squall she knew or keeps forgetting he's not her Squall and mistakenly treats him that way.
Another thing you could do is put Rinoa in, knowing who Leon is and Leon knowing her and all that. But you'll have to give her an altered background. You could write her as someone who lived with the rest of the Final Fantasy cast in Radiant Garden, or you could make her someone he met in Traverse Town. Or make her a spectator in the Olympus Coliseum who was amazed at the way he fights. Be creative!
This doesn't just apply to Rinoa, but to any other FF canon character with relations to the KH FF characters you may want to put in, whether it's Celes, Zidane, or Seymour. It's tough to do and requires lots of planning, but it can be done. I've seen too many fics that take the easy route and just follow FF canon when KH canon should trump. Then you're not writing a KH story. You're writing a FF story that uses KH's setting.