Title: Calculus
Pairing: Riku/Sora

Warnings: fluff
Rating: PG

Word count: 886
A/N: This was originally part of another older fic, but I'll keep this as a separate episode.
Disclaimer: I don't own Kingdom Hearts, but I do get a kick out of writing for the fandom.

Summary: Kairi comes face to face with the depth of Sora and Riku's relationship after they return home. [drabble – Sora, Riku, Kairi]

When Sora began dating Kairi upon their return, his bafflement with the world greatly intensified. All of his previous experience pointed in this direction: Boy takes on Evil, Boy rescues Girl, Boy defeats the Big Bad and wins Girl's heart . . . and they live happily ever after; Sora mentally went through the checklist, pausing perplexedly at the last. The formula was simple, direct, and seemed like a genuinely natural progression. Sora was the Keyblade Master, Kairi a Princess of Heart. 1 + 1= 2.

But then, Sora had never really been very good at math. Maybe he missed something in the basics, he mused.

Lack of mathematical skills or not, Sora couldn't quite shake the feeling that there was something terribly wrong with the whole picture. 1 + 1 was not equaling 2 . . . maybe he was a square root or something irrational like that. But these are not things one should be thinking about while kissing your girlfriend.

Which was why Kairi pulled away from the kiss Sora had long since lost interest in awkwardly and stared at him strangely. Riku had often joked that Sora could sprain his brain thinking too hard, and it looked as if he'd done exactly that in the process of the kiss. Kairi swallowed and cleared her throat, looking down at the couch. When there was no response she cleared her throat again and prompted, "Sora?"

Sora's eyes snapped to her face from la-la land and widened in an almost comical fashion. "Kairi?" he asked meekly, a blush already spreading across his cheeks.

"Are you ok?"

"Uh . . . yeah."

"You . . . lost interest," she said awkwardly, feeling his heart waver.

"I . . . got distracted," Sora answered, equally as awkward. He was brimming with shame; he could hardly imagine the Beast being this distracted when he was with Belle.

"Oh."

Where was the happy ending he thought they were supposed to have, that would magically appear, that should have appeared once he and Riku had returned from the dark beach? Maybe it was holed up in the Destiny Islands customs department; they were terrible about letting things through in decent time, he thought bitterly. "I'm sorry," he said quickly.

The doorbell interrupted their increasingly lurching conversation, and Kairi was startled to feel Sora's heart nearly swell and rocket sky-high. Sora leapt up and bolted for the door, tearing the portal open. Glancing over the back of the couch, Kairi saw Riku standing in the doorway. She sighed a little bit, acknowledging her alone time with Sora had come to a screeching halt.

"Hey man," Sora said excitedly. "Come on in!"

"Am I interrupting something?" she heard Riku ask quietly with a raised eyebrow, eyes flickering over towards her.

Sora shook his head, smiling nervously as Riku walked in, nodding and grinning over at Kairi. "What's up?"

"Not much," she answered. "Ready to watch some movies?"

"Sure," Riku said, plopping down on the other side of the couch while Sora hopped over in the middle between them.

Kairi looked away, her throat suddenly dry; Sora's heart was warm and content, alive with feeling where it had been quieter and unsure not moments before. Sora and Riku were already talking animatedly together.

She turned on the DVD player.

*

Several hours later the room was only lit by the TV, illuminating the two figures on the couch. Kairi returned from the bathroom distractedly, but stopped abruptly when she saw Sora and Riku sitting together.

Sora was leaning heavily on Riku's side, his head lolling against Riku's chest with a peaceful expression on his face, snoring adorably. Riku's cheek was pressing lightly in the other boy's hair, his own breaths catching in Sora's spikes, making them move. She could see Riku's fingers curling around Sora's upper arm comfortably, maybe a little possessively. Anger welled in her chest – Sora was her boyfriend. What right did Riku have to hold him like that? Even as she frowned and got ready to say something, Riku cleared his throat quietly.

Kairi started and gulped; Riku's ocean-blue eyes glowed in the TV's light as he returned Kairi's gaze evenly. She knew, then and there, that nothing could tear Riku from the other boy. Their bond was something more than she could ever want to come between, and she realized that maybe she was the one being selfish. Maybe she was the one intruding.

They shared a private, silent exchange, which ended with Kairi nodding with a small, quiet smile. Riku relaxed against Sora, his eyes shifting back to the TV as he hugged the other boy closer.

When Sora woke up a few minutes later, sensing the relaxation in Riku's arms and through his heart, he blinked sleepily up at the older boy. "Whassup?" he mumbled.

Riku smiled and shook his head, readjusting Sora in his arms. The brunet sighed contentedly and closed his eyes, refusing to contemplate the mathematics of all this or what number Riku was adding to his own irrational one to come out with a perfect answer. Maybe it took two Keyblade Masters sometimes, he mused sleepily. Math had nothing to do with it.