Kingdom Hearts, Kairi/Sora/Riku, first time(s)
"Hey Riku, wanna come and have sex with me and Kairi?" was NOT how Riku'd ever pictured Sora to talk to him (for real, that is) although it'd shown up in a few daydreams (and wet dreams).
So when he lets himself in to their secret hiding place, and sees Sora and Kairi there, playing with each other, naked and undressing, he's just a little left out and feeling overdressed.
As he turns to leave he scuffs his foot on the ground and Sora and Kairi still their frenzied moaning and jump him, Kairi's top hanging on by one strap (that's all he remembers, anyway) before they pull him into a boiling embrace, all lips and tongue and teeth and hands sliding down his pants to find his balls, exploring the join between his balls and his dick while Sora's other hand helps Kairi's other hand in taking off their shirts.
And when they're all naked (except for Sora, whose shoes are the very devil to take off - the laces are waaay too complicated for animal lust to unwind -) the light of the opening exposes a patch of warmth on all their bodies as they twist in previously unimaginable positions.
There's a flash of a strand of hair hangs down where Sora's dick pounds into Kairi, her mouth open in a gasp, Riku running his hands down over their bodies and exciting them all unintentionally - he's never done this before and doesn't really know what to do, but he just likes how immature Sora knows exactly what to do all the time here, and he just likes the feel of Kairi's satin curves against his fingers.
And then when Sora leans down and flicks a tongue tip over the edge of his cock he, embarassed at lasting this short, explodes over the brink and begins to fall apart Sora just laughs and watches Kairi with knowing eyes; indeed, she's watching Riku with wide eyes and clenching muscles, a moment before exploding herself -
And Sora doesn't even try to keep his own in.
He throws his head back and laughs, full and deep and finally complete.
And they're lying there, dazed on the floor of their hiding place as the light outside them dims into an indigo night.