The more I think about it, the more I believe that things might be one of the most important scenes of KH3. KH3 is a fucking Soriku goldmine, and I could blog about them for years to come, but this is the scene that sets it all up.
We see from the get-go that Riku has changed. Being named a Keyblade Master has given Riku a huge confidence boost. Combined with finally recognizing his feelings for Sora for what they are (after spending weeks in Sora’s dreams and diving into Sora’s heart in Dream Drop Distance to save him), he’s completely at ease with himself and the world around him. He’s got this quiet confidence that he never had before. He smiles, despite being in the Realm of Darkness. He’s finally comfortable in his own skin. Somehow, he doesn’t know why, so Mickey goes and explains it to him (and us, the audience).
“What’s wrong, Riku? Are you tired? Do you need a break? We can stop.”
“I’ve been here. I should know this place. But that all seems like another life.”
“Well, gee. Think of all you’ve seen! All the feelings you’ve felt. Why, you’ve done years of growin’ in almost no time at all.”
“I remember my first time here. I was so scared. But now, my doubts and fears are gone. If anything, I feel exhilarated. And it’s not because there’s darkness in me - I know too well what that rush is like. This is different. And it’s not adrenaline either. I know Aqua needs us…but I’m ready. I’m in control now. Maybe it’s because you’re with me this time.”
“It’s not me. I think it’s because you’ve finally found inside you that special strength to protect what matters.”
“What?”
“Sometimes you care so much for somebody that other feelings disappear. And then, there’s no room for fear or doubt.”
“Is that it?”
Mickey spells it out for us all: “you have a lot of feelings”, “you care so much for somebody”. There’s only one person this somebody could be, they might as well have come out and said it: Of course it’s Sora.
And then, at the end, that wistful smile… Riku knows. And he’s okay with it.
TLDR: RIKU HAVING FEELINGS FOR SORA IS CANON KINGDOM HEARTS.