something I've been thinking about for a while now is how the paopu fruit was introduced to us in KH1 as a symbol of romantic love, but as the series went on, it slowly became clear that it can actually also be a symbol of love in general.
in KH1 and CoM, the legend surrounding the paopu fruit is explicitly romantic. Selphie tells us this directly, and Riku implies it when he gives the fruit to Sora. it's a symbol of a deep connection that holds no matter how far apart the hearts that share it are.
as for how this symbolism is applied to the relationships in the game... Sora is implied to have (supposedly) romantic feelings for Kairi when he draws himself giving her a paopu fruit in the secret place. and as I've already mentioned, Riku gave Sora a fruit and followed it up with a confirmation of what the legend implies about those who share it. the way he phrases it even makes it sound like he's trying to see if Sora would share one with him. and of course, Kairi gives Sora her good luck charm, which is clearly meant to look like a paopu fruit and represents the same thing as the fruit itself. so there's a bunch of romantic implications all around in KH1.
then in CoM, Kairi's good luck charm is transformed into Naminé's version of it, which looks even more like a paopu fruit than the original charm. the whole game heavily implies that whoever Naminé replaced is someone Sora had romantic feelings for. we are initially supposed to assume this person is Kairi, but with the context of the Japanese version, it becomes clear that it's not her. it's "aitsu". not super relevant, but it is an interesting continuation of the love triangle implications in the first game.
then there's Birth by Sleep. this is where the series takes all the romantic implications and turns it on its head.
the wayfinder charms are a representation of an unbreakable connection shared between Aqua, Terra, and Ven. except here, it's clear that the implications are platonic rather than romantic. and the thing is, the wayfinders look exactly like Kairi's good luck charm. Aqua even outright says that the wayfinders are a Destiny Islands thing, they're supposed to be made with thalassa shells instead of glass, and they are explicitly shaped like paopu fruits. y'know, the same fruits that represent deep connection.
here's where it gets interesting to me. Kairi's charm is obviously a wayfinder, a proper one made with thalassa shells and in the image of the paopu fruit. and we are told that the wayfinders are platonic, and giving them to a friend is a way to connect your hearts no matter what comes your way. I think this makes the intention behind Kairi's wayfinder platonic rather than romantic. not to say that she didn't potentially have romantic feelings for Sora, just that she was telling the truth back on the Islands when she said the wayfinder charm was meant to keep all three of them together (rather than just Sora and Kairi). sure, she only made one, and she gave it to Sora, but that doesn't change the fact that the paopu fruit shape in this case represents platonic connection between Kairi and her best friends.
so what do I think all of this means? well, let's look at where the paopu fruit appears after CoM. the first notable appearance is as Kairi's keychain for Destiny's Embrace. then it shows up again as the keychain for the combined Keyblade. I'd like to point out that it's only the keychain for the combined version; when separated, each half of the combined Keyblade has a heart shaped keychain instead.
here's my theory. when it comes to representations of paopu fruits like the wayfinders, I think they generally only represent platonic bonds. when it comes to the actual paopu fruit, the number becomes more important. a single paopu fruit shared between two people seems to have romantic implications, while exchanging paopu fruits with one another is platonic. the only instance we have of two people actually sharing the fruit is in KH3, when Sora and Kairi exchange paopu fruits. that instance is also confirmed to be platonic in ReMind. but there's mentions of it before then that I already mentioned, and they all seem to point to the same conclusions.
TL;DR: one paopu fruit is romantic, multiple is platonic. I think it's still possible that things like Sora drawing the fruit and Kairi giving him her wayfinder are intended to be read as romantic, given that Riku only gave Sora one when he was teasing him about sharing it with someone (& also what Selphie said about the fruit). but things change, and the series has proven that Sora and Kairi's feelings for one another are platonic now. meanwhile, Sora and Riku have a combined Keyblade with the paopu fruit for a keychain, sooooo... yeah.
