I was vaguely aware of the FInal Fantasy series, but hadn't played any of them. I came to Kingdom Hearts because of the Disney, and didn't know the Final Fantasy characters weren't original characters until I read Jiminy's Journal. Then I did research on the series. I don't think my experience is very typical, though. I know that's not really what you were after, but KH did bring me to the Final Fantasy games.
Pretty much this (I got into KH soon after KHII was released). I also remember being somewhat curious about the games, and wanting something to tide myself over while I waited for KHIII (how little I knew back then. LOL.), so I checked them out, since I already liked Square.
Plus, a lot of my friends loved the series and thought I was weird for not knowing it (and I think they were getting annoyed with my KH talk, so they wanted to get me into FF, so I'd have other games to obsess over. LOL.), so first I watched Advent Children with a friend. And then after that (after looking things up on YT), I bought FFX and X-2 (and for some stupid reason was playing both of those at the same time at first), and suffice to say I became o
bsessed with FF, and started playing my way through as many of the games that I could.
ANYWAY, I could get more into my FF history, but since this thread isn't about that, I'll get back on topic. After I knew the characters, I really enjoyed seeing them in KH. And liked feeling as though I was in the know. LOL. I also went through a dark phase in thinking the Disney should be removed from KH in favor of the FF (when I was really obsessed with it), but quickly changed my mind about that. LOL.
And when I saw Zack in BbS... I definitely was very happy, and promptly freaked out. It helps that I love CC and Zack's one of my favorite FF heroes, but I really loved his appearance. I think it worked really well, and I liked how they used his theme, and had a reference to his asking Aerith out on a date. LOL. My only regret is that they didn't end up including Laguna in the game after all. XD
And in DDD, when I saw the TWEWY kids (sorry if you don't want me to talk about TWEWY here...), I about lost it. Unlike FF, I'd known about TWEWY beforehand (as a friend of mine owned it, and I was interested in it as it was by Square and seemed KH-ish; the music, and things I'd seen on YT were also nice), but I didn't finally get around to playing it until Neku was first revealed to be in 3D.
But, yeah. I ended up playing it
right after that (and quite a while before 3D came out), and my gosh: their inclusion was flawless. TWEWY is my favorite game now. And I thoroughly
adored seeing these beautiful, underrated characters again. And I loved the humor they brought, and how they meshed with the KH characters so well.
It was also great to seem them completely animated (and three-dimensional), and to hear more of the voice acting... And the fact that their appearance in 3D furthered the TWEWY story somewhat and could, possibly, tie into canon... It was good. It was so very amazing to see them! And the references! And the Joshua character development! I can't even-
Anywho, I imagine when I see FF characters I know in future KH games (or other Square or Disney properties), I'll be just as thrilled