A/N: Written all in one sitting, unedited, I haven't even read through it, lol whoops enjoy it anyway
Maybe they're quiet because they have to be, sneaking around in her thin-walled apartment, giggling and shushing each other and hoping to God her mother or brothers don't find them out.
When it's midnight on a school night and they're kissing on her bed, shoes off, shirt off, and she wordlessly fumbles for his zipper, and the need for vocalization has passed. This is routine, not that it still isn't new, but Peter has long since memorized the feeling of her hands on his back, fingers clutching, and how her legs wrap around him. They have come a long way from their first days - of shaking hands and awkward, breathy laughter and not lasting much longer than the length of the Ramones song playing quietly in the background.
He loves looking at her beneath him (or above him, whichever position they've taken for the time being) when her lips aren't on his. She smiles at him, coy but inviting, and looks down between them, watching him sliding into her. He's used to the feeling of being between her legs, feeling like he'll explode any minute, holding on until he can't anymore - but at the same time it's so new, so overwhelming, and he loves her so much. The way she closes her eyes and opens her mouth into a silent 'o.' The way she digs her nails into his shoulders and back, scratching just hard enough for him to like the pain. The way she moves with him, under him, her hips following him and encouraging him to thrust the way she wants it. The way she's unashamed to ask for more, to whisper, "faster," or "touch my clit," insistent and demanding and coming from this soft harmless body beneath him.
He loves her so much. When they fight, it's a different kind of passion, loud and angry, as if they can't do enough to be heard by the other. This release of tension and passion is different - quiet, soft, harmonious. They hear each other without making a sound.
He loves the sounds she does make, though. Quiet whispers of whimpers, little breaths in and out, sighs and the occasional gasp. He wonders if she would be louder if she had the chance, and decides he doesn't care. He loves her loud and soft. He loves the thought of making her scream, but this is quiet perfection in itself. Her eyes squinted shut, her head thrown backwards, her brows furrowed and her mouth open. She's almost always silent when she comes - it's an escalation of sighs, and sighs, and sighs, and sighs, and then silence as she shakes, holding onto him, keeping him pulled deep inside of her until she's done. When he's lucky, he comes with her, teeth gritted and eyes open and blinking rapidly, trying his hardest to keep watching her.
They're very quiet together. It surprised him at first, but now he thinks it suits them well. They whispered with each other the first time they kissed, and the first time they found conflict with each other they were speaking softly on the floor of her bedroom, and when they broke up his voice was stammering and soft, and when they got back together he uttered hushed apologies to her over and over between kisses, and she forgave him the same way, although it took her more time. So it follows that they're quiet in their most intimate moments, as if making love, like the things they tell each other that no one else knows or can know, is a secret.
When Uncle Ben gave Peter the Talk back when he was fourteen years old, he had warned Peter that when he had sex he would want to tell the world. "Don't," he had said. "Respect your partner." That speech was unnecessary, Peter now thinks. He doesn't want anyone to know about Gwen's sighs of pleasure, the concentrated look on her face, the way she knows how to ride him. He doesn't want anyone to know about the things she knows how to do with her mouth (or the fact that she likes doing them), or the way she scratches at his skin, or the way she laughs in breathless relief just after she's come. It's not about respect - he respects Gwen, but his desire for secretiveness has nothing to do with that. It's selfish - he's selfish. Like a spider, he wants to keep her for his own - her image, her noises, her body - tangled in the web of his arms and legs. He wants this to be the one wonderful secret they share together - nothing that has to do with secret identities or laboratories. Just the knowledge of what it's like to be exposed to another person, completely alone and completely together.
After, they cuddle, a quiescent pile of body on body. She plays with his hair, he presses kisses to her hands. They whisper jokes and stories to each other, laughing soundlessly. If she falls asleep, he leaves her, cocooned in her blankets, to return home. If she doesn't, he stays with her until there's nothing he can do but hurry home in time to make it appear as if he's been in his own room all night. And if Aunt May has any suspicions, she doesn't voice them.
Peter was told once that secrets have a cost. If that's true, he wonders what the cost of loving Gwen could be. What could come of these quiet moments, of sighs and whimpers and shimmering bodies?
He doesn't spend much time worrying about it. This is the best secret he's ever had, and he's determined to keep it quiet forever.