A/N: I wrote this ages ago, when I had the same realization as Hermione. I tweaked my story a bit to fit her. Enjoy.
SSHGSSHG
Growing up, Hermione had never thought that her bedroom was particularly small. Her parents being well-off dentists gave them the opportunity to provide their only daughter with a large house to grow up in, including a rather lovely bedroom. Even as Hermione aged and objects in her room were replaced— a larger bed, a smaller desk, a bigger closet, more bookshelves— the room still never managed to seem small. That was until Severus came to stay the night.
It was in the middle of the summer and her parents were away at yet another dental conference, most likely discussing everything from the latest in whitening technology to the long term effects on surface enamel from continued exposure to semen. So, Hermione had invited him over for a sort of domestic muggle night— dinner, movies, the usual. And having him in her childhood home, though strange at first, managed to feel comfortable. To feel right.
Until he was above her, on her bed, pounding into her, one of his hands clenched behind her shoulder, the other wrapped around the headboard of the bed. She could hear the wood bang into the wall with every snap of his hips.
Despite the beauty of their own little domestic night together, looking back on it, Hermione still couldn't help but feel that her bedroom was changed. Somehow made smaller. All because of the indents on the wall above her bed from the banging and thrusting and growling and even the cuddling afterwards. Her childhood room felt so much smaller to her now, all because a much larger man got his hands on her headboard.