Sharp, filed teeth line Sans' mouth. He has no lips, no tongue, not even gums, or a soft palette—there is nothing appealing about it. It is a mouth meant to tear and rip with each bite. There is nothing tender or gentle about the way light glints off those teeth.
Looking at Frisk and the attention they paid to each jagged tooth though, you wouldn't know that. Their tongue is slick in his mouth, exploring, caressing. Running across every ridge, tasting, tracing the edge of each tooth. His teeth are sharp enough that if they aren't careful, they'll cut their tongue on a tooth—he's tasted their blood before, the magic of his body telling him its metallic tang.
He honestly has no idea what they get out of it, but he doesn't stop them either. Really, he shouldn't be getting anything out of it either—his magic isn't that good at telling the taste of Frisk's mouth and he has to stay perfectly still or he might accidentally slice their tongue open.
And yet.
Once again, they are in bed again, paperwork scattered around them, forgotten. One paper is being crumpled under Frisk's right knee, but neither of them cares. The bed is technically Frisk's, but the two nod off so consistently each night as they look over paperwork that Sans never sleeps in his own bed in the bedroom downstairs. Now that room just sits empty while he sits in Frisk's bed.
Frisk is humming something, the noise reverberating in his skull. He doesn't mind—it's a pleasant sound to go with the pleasant feeling of their tongue sliding against the back of his teeth. Their right hand presses against his shoulder to steady them, but their left cups his jaw, their thumb idly rubbing circles against it. It takes a strong perfume for him to smell anything, but Frisk is so close, he can smell their natural aroma filling his head. Sound, smell, and touch would be enjoyable enough, but it's the sight of Frisk that sells it.
How many people get to enjoy this vision now? No one but him, that's who—Frisk is an accomplished flirt, sometimes straddling the line of inappropriate during work, but Frisk is also faithful to a fault. No one else can see Frisk's face, content and at ease, the tension from their long day of work already drained from the lines of their body. They sigh against his mouth and he can't stop the shiver running down his spine. They chuckle and sweetly kiss the corner of his mouth, perhaps the safest part of his maw.
Somewhere downstairs, a clock chimes one. Frisk sighs and pulls away to press their foreheads together. "We should probably go to sleep," they murmur, but their voice is husky and their eyes glitter darkly. "But that'd be boring."
"Yeah," he manages. "Might want to get the proposal from Mister Katsuki out from under your knee though."
They pause, frowning down at the offending piece of paper. They pry the sheet out from under their knee, glancing at it but not bothering to read it before they casually toss the paper over the side of the bed. "Whatever," they sigh, reaching for him again. "I'll just print a new copy later."
"Well, if that's the way it is," he replies before tossing the stack of papers that had been by his side off the other side of the bed. There are other piles of papers, ones that they just can't reprint, but he just thinks fuck 'em. Who gives a shit about papers when Frisk is looking at him like that? He leans back, tugging them forward to press against his rib cage. He can feel Frisk reaching for the buttons of their pants, but he's more distracted by their tongue idly tracing the edge of one of his canines. He obliges them, opening his mouth to them.
There is no tenderness in his mouth but that which Frisk leaves there.
A/N: This chapter's written in present tense. Because why not. This was the second oldest side story I have, which I wrote all the way back in January.
Anyway, I figure it was time I lived up to the claim of Sans/Frisk in the tags.
Geust: Thanks for the warning on the "dressing room" bit-I went back and changed it after you said something. Much appreciated. The last chapter was fun to do-mainly because all I had to do was paste in the dialogue from Chapter 12 and then rewrite around that. It got written super fast. I know you said you weren't a big fan of Frisk/Sans, so I hope this chapter wasn't too awful for you.