scribbles
Children. They'll draw on anything, won't they? Pretty much. Nothing was different about that for Kairi, either - upon invitation into Sora and Riku's 'secret cave', she too, scribbled drawings on the walls alongside them. The most iconic of these however, is the flashback scene in which we see Sora and Kairi etching each others faces into the stone. Symbolic? Partially. It shows their friendship standed for a long time. Actually, these drawings play a rather big side role. Papou fruit is first introduced in a discussion between Selphie and Sora, in which, Selphie tells Sora that you 'give a Papou to the person you love. Your destinies become intertwined'. Later on the same day, Sora's in the cave, reminiscing about he and Kairi drawing on the walls. Absently, he etches a picture of a hand giving a Papou fruit to Kairi.
Unfortunately, the islands are destroyed before Kairi as much as glimpses this. When the islands are reformed, however, we see her going into the cave by herself, looking thoughtful. Perhaps she feels it's a place she can 'connect' to Sora - they have some precious memories there. She gazes upon the walls, and looks momentarily surprised. She's seen the drawing of the Papou. Her mind's eye sees Sora drawing it on the wall, and smiling - and she starts to cry. This is the only time in either game she cries. Tears of joy, happiness, I suppose. The shot them zooms out as she kneels on the floor, and next we see Kairi's hand offering a papou in return.
Papou is signficant for Kairi and the others, more so for Kairi. The general idea of sharing a Papou is a more of a girl related thing, and Kairi even keeps with her a lucky charm in the shape of one. Her charm is slightly multicoloured and looks like a flower of sorts, with a shading of brown hair on top of one point. This is probably Sora. She gives it to him as a promise that he will come back to her in Traverse Town. In the end, he does come back, bringing out the charm form his pocket, and then grasping Kairi's hand and giving it back to her. A promise fulfilled.
The next time we see this caves is right before the ending of KH2, with the letter. During the credits, what happens to each world is resolved. Then, there's a shot of Sora, duplicating Kairi's steps the time she returned. It's almost identical in everything she did, and he too looks surprised for a mere second as he looks at the wall, and starts smiling to himself.
Pairings, couplings, have special items, right? I personally believe the item for Sora and Kairi is the papou fruit, but even more so, the caves. It's a very very small add on story about them, but it has so much love behind it all. When I was busy in my overjoyed state of beating Kingdom Hearts II, I calmed down and began crying as I saw Sora walk into the cave. I was smiling, since I knew Sora would be happy. It's so symbolic, it's hard to explain. It's a message for all time, like marriage is a way to declare one's love - it's a bond they share which no one else has, which makes it special, a unique love. Overall, Papou Fruits and Caves are important in Kairi's life.