It's a few months after the conclusion of The Second Keyblade War, and Lea can't help but constantly compare the new, thankfully not-a-Nort Isa to his once-upon-a-time best friend who loved stars and the color green and dogs.
New-Isa doesn't talk much. He doesn't eat much either (unless Lea threatens to shove the meals down his throat). New-Isa writes a lot, mostly in a thin black notebook that reminds Lea eerily of the journals they kept in the Organization, and he never tells Lea what he's writing (which bothers Lea, because… well… he has to know). New-Isa cuts his hair in a similar style to Old-Isa (actually, Lea cut it), and he spends a lot of time inside. He'll go on walks with Lea, of course. They don't talk much on these walks, but it's one of those understanding silences, and Lea thinks Isa needs these more than cheesy jokes and lame puns (except Lea's puns aren't lame).
New-Isa is different from the boy Lea once knew. Very different. When Lea broods on this after training with Kairi one day, she gives him a sharp look (for some reason, the girl has decided that Isa will be her new project) and responds, "Well, then you have the chance to meet him all over again. Stop expecting him to be his teenage self. He's not. You aren't, either. You're both different, and there's reasons why you've changed and can't go back to how you were before. So stop expecting everything to go back to how it was when you were kids, and just get to know this new Isa. Maybe you'll like him better than you're thinking you will."
Lea thinks about this after every nightmare Isa has ends in him acting as if he can't hear anything Lea is saying; after every argument that ends in yet more jealousy and anger piled on the mountain that is the brokenness between them; after every vaguely anti-Roxas-and-Xion remark Isa makes. And at first, Lea decides that Kairi is completely wrong. New-Isa is not pleasurable to be around at all.
But then come the times Lea puts his elbow on Isa's shoulder like he used to do when they were kids, and Isa doesn't pull away or shrug him off. He doesn't even grunt at him in disapproval. There are the times when Lea is exhausted (screw Eraqus for his unreasonable mission hours), Isa makes him coffee (or gives him a beer, depending on how much Lea felt like punching someone), and they sit in silence casting looks at each other filled with "sorry" and "I forgive you". There are the times when Lea notices Isa smiling at a joke someone's made. There are the times when Lea catches a faint glimmer of that boyhood mischievousness in Isa's eyes.
And in those times Lea can't help but wonder if Kairi may someday be completely right (although he'd never admit this to her).