"i mean i know that she's grown…but damn," you speak to yourself while removing your hoodie, running a hand over your skull. "so that mess in Paps room was just so she would have something to bone." You laugh at your pun. "though if she's willing to sneak in there and take one of his bones, she must still really like him." You frown at the thought. Not that your brother isn't someone worthy but you never knew she still felt that way about him, she never mentioned it again after their first date ended with her in the 'friendzone' years ago. And here you thought you knew her best; well you definitely know a lot more about her now.
Replaying the scene in your head, you start feeling the uncontrollable swell of your magic again, affects her lusty image had on you. Running a boney hand over the blue magical bulge, you decide you should have some fun too. You remove your slippers and shuffle out of your t-shirt, shorts and boxers. Climbing onto your bed you position yourself how you imagined it would be if she was on top of you. You lightly grab hold of your erection, slowly stroking it from the tip to the base. Closing your eyes you focus on the memory of her back swaying in motion, the sound of her labored breathing; watching her as she thrusts herself on to you moaning for more.
"Oh god… Sans…" Her body sweaty and hot to the touch, "Sans… Please! Don't s-stop!" she moves with more need, making you want thrust up to match her hip's rhythm.
"you got it babe." You reply back, increasing the pace for her. You drag your fingers down her spine slowly tracing out her vertebrae causing a pink trail to follow. The action causes her to arch and moan out while she thrusts. The friction feels so great over your cock, so warm and wet; you start to wonder why you didn't start doing this sooner. You can feel the pleasure welling up inside you, sensing your own release coming.
"Getting close…" Her hands grasping her thighs with anticipation, you continue to drag your fingers along her back, tracing out more bones along the way. "S-so good when you… touch.. ah" you watch her hands switch to grasping at her chest squeezing and tugging from behind her back. "S-sans, I'm… there… ffuck…!"
"then i guess you'll really like this." You give her ass a quick slap then wrap your hands harshly around her hips pulling down and thrust as far as you can. You're enjoying the sensation of her pussy tensing and squeezing around you, her hips buckling and convulsing uncontrollably on top of you; using you to ride out her pleasure to the fullest. "told ya so." You hummed to her while she attempted to calm her breathing. She glances behind herself, giving you a smile, which you're sure she meant to be innocent looking, but with the way her face was flushed from pleasure just increased your arousal.
Increasing the pressure and speed of your hands on yourself, feeling the sensation bubbling you over breaking point, "f-frisk..!" you climax hard onto your hands and the sheets of your bed. Heavy breaths filling up your room as you open your eyes to see the mess. Letting out a sigh, you dismiss the magic watching it fade off of you and your bed. Running a hand across your cheekbones you can still feel the heat from your blush. Using your close friend as spank material made you feel a bit guilty, but then again hadn't she done the same? Feeling the cold air run across your bones now that you were sweaty, you decide to lazily put some boxers back on and cover yourself with your blanket. Closing your eyes to think about what you had experienced today, you fall asleep.