Stiles felt himself holding his breath as Derek pressed closer to him. He knew what was coming and he was excited for it. He wanted it. He let himself be moved around as Derek wanted, whimpering at the brush of Derek's head against his thigh, at the little trail of precome left on his skin.
Leaning up into the kiss, Stiles parted his lips eagerly, short as it was. He knew Derek would want to watch, would want to see himself pushing into Stiles for the first time.
He let out his breath in a shudder when he felt Derek's head brush over his rim, slipping through his slick as it moved back and forth. Stiles whimpered, trying to keep relaxed, letting out a filthy, wanton moan when Derek finally penetrated. The crown stretched him slightly before Stiles settled around his shaft - and he was right, it was just thicker than three fingers.
God, his mate sounded so beautiful. He sounded so good, making those sweet little noises, as though it were the best thing he'd ever felt. The gentle easing, the drag of Derek's cock as it moved inside him, felt as though it were setting Stiles alight.
He arched his head back, offering his neck to Derek to press against or kiss or bite as he so wished, breathing in short, staggering gasps as Derek filled him slowly.
They'd do this in a few months- they'd do this and Derek would come inside him, put a baby inside him. Knot him. Breed him.
"Oh, fuck-" Stiles whimpered as a wave of pleasure washed through him at the thought. Derek would knot him. They'd be joined together. His mate would fill him over and over again-
He feels Derek bottom out, feels the very slight swell at the base of his cock that teases his rim but slides in easily. Stiles doesn't know if he wants gentle lovemaking or if he wants Derek to pound him into the bed, but slow is probably for the better if they want to try and make this last. And he's really enjoying the feeling of Derek inside him. He's enjoying the feeling of being full.
"Der-" Stiles rasps softly, dragging his blunt nails down his mate's back. "Derek. You feel so good." His words come out in almost a sob, trying hard not to clench, trying not to move too much, to just enjoy the sensation. It doesn't hurt like he'd worried it would. There's a little stretch, but it's good. Derek fits wonderfully. And Stiles can feel the pulsing of his knot gently just inside him, can feel Derek's length resting against his prostate. "I think I could come without you moving," he manages to whisper. "I could come- oh God. You feel so good. Can feel your knot growing, baby. Can feel you swelling for me."