Sora and Riku never really moved from where they sat. There was no need to. They continued their kiss even while Kairi announced the start of the festivities, only deepening it and turning it into a wet make-out session, complete with cupping each other's cheeks. After a short while, their hands started to roam each other's bodies.
Given how long the two had been best friends, their movements were in a rare sync, despite this being their first time with one another. Sora's hand rested on Riku's shoulder and chest, Riku's ran itself up and down the brunette's sides. Sora eventually broke the kiss to sit on his best friend's lap and start sucking his neck.
The silver-haired boy closed his eyes, moaning softly as his head leaned back, unprepared for the assault. In response, he let one of his hands go down and cup Sora's crotch, rubbing it softly. He grunted and sucked harder, fully intent on leaving multiple marks on the taller male, while also returning the favor and reaching down to feel Riku's growing erection.
Things quickly escalated, turning from casual rubbing to jerking each other off through their pants. Riku was the first to take things further, reaching into the other's pants and boxers to feel his bare length, a gesture which Sora promptly returned. Neither were sure when Sora got off of Riku's neck, though they were both staring into each other's eyes and kissed some more as their friendly competition of one-upsmanship began even here, an unspokenly agreed prize on the line between them.
Riku squeezed Sora's dick, Sora moved down and started playing with Riku's balls. The silver's toes scrunched in his shoes, and he smirked. "Time to strip, Sora."
Sora nodded, thinking much the same thing. They broke apart only long enough to remove their pants and boxers, then pounced back at each other, like a pair of hungry predators. Their lips crashed together once again as Riku pushed Sora onto his back, grinding his erection against the other's, causing both to moan aloud and Sora to grind back.
Despite them giving each other the same movements, the sensations were slightly different, due to Riku being slightly bigger than Sora. Meaning his length covers all of his companion's, while his own could only be felt in pieces. Either way, both were exceptionally pleasured from the friction. They continued to rub up on each other, Sora reaching around and slapping Riku's ass - a gesture Riku couldn't return, due to Sora being pinned onto his back - and the taller boy responds by pinning Sora's wrists over his head.
They were both panting and moaning rather loudly now, both of them getting rather close. With an incredibly great deal of effort, Sora managed to avoid peaking first, even as Riku exploded all over their chests and Sora's cock.
"Hah...hah..." Sora stuck his tongue out as their kiss broke again. "I win," he whispered, gently caressing Riku's cheek. "Yeah...somehow you did, didn't you?" Riku smiled and closed his eyes gently as they both took a moment to recover - and in Sora's case, back away from the edge. "You ready for this?" Sora asked after a moment. Riku shrugged and laid back, waiting for the other to begin. "We'll find out," he answered, "I always figure our roles would be swapped."
Sora smirked and licked his lips. When he was ready, he held Riku's legs apart and lined up before pushing in. Both of them moaned louder than before at this; Sora due to Riku's tightness, and Riku due to never having been penetrated. The silverette's eyes snapped open as Sora slowly, gently pushed all the way in until he was fully sheathed inside the other and their hips collided, Riku's lungs forgetting how to work momentarily.
Sora felt a bit bigger than Riku anticipated.
Sora not-so-patiently waited for his friend to let him know it was okay to move. When he finally did, Sora leaned down and kissed him, reaching down to stroke Riku's dick some more to help distract him from any pain as well as add to more pleasure as he started to move. Pulling out almost to the tip, then pushing back in, he took his time in letting them both adjust.
After a little bit of time though, Riku's arms slipped around Sora's shoulders. "It's okay," he murmured between his moans, "you can go more. Like you want me."
Sora grinned and nodded. "Right." With that, he gradually picked up the pace, continuing to thrust in and out of Riku and jerk him off while kissing him deeply. Riku had already recovered from his orgasm and was amazed that Sora hadn't had his own yet.
Keyword being yet, as Sora was getting extremely close now, and Riku didn't even need a verbal indicator with how much Sora was throbbing inside him. "L-Let it all out Sora," he managed. The brunette was being worked into a frenzy as his thrusts were starting to hit Riku's prostate, causing the latter's vision to blur some. His legs slipped down from Sora's shoulders and locked around his waist, locking him in and preventing him from pulling out. Not that he wanted to.
"R-RIKUU!" Sora called out as he finally came, legs shaking a bit as he continued to thrust, milking himself for all he had. Riku could only moan and groan now, riding out Sora's climax as best as he could from underneath.
Sora finally slowed to a gradual stop, and they simply laid there, panting heavily and resting their foreheads against one another affectionately.
"Sora..."
"Riku..."
The two smiled and laughed a little bit. "Don't forget this," Riku started, "because soon it'll be my turn to get you back."
Sora smirked. "I look forward to it."
So before we move on, I have a question for you all. Who was ready for Sora to top Riku? I actually wasn't, myself! ...granted, you as the reader might have, considering the chapter is named "SoRiku" rather than "RikuSora" or something. Also, I'm doing a pattern to avoid things becoming repetitive for me. I'm doing no more than one hetero in a row. Thus, it'll go het yaoi het yuri het. Meaning you can probably guess when and where we'll get to Kairi and Aqua. The question remaining is...who's next? ;)