“…WANNA DRAG YOUR LIFELESS BODY TO A FOREST & FORNICATE WITH IT.”
synopsis — smutty part two of sinister mark coming into the universe with one goal: to find you, as you’re dead in his universe and every other one he’s searched. you’re only friends with the original mark but sinister is obsessed with you. things go slightly south and now you’re hiding sinister from everyone in the comfort of your own home.
sinister invincible ✘ m reader
contains — pillow prince reader, dumbification, drool + spit used as lube, creampie, fingering, dick riding, deep throat, doggy-style, biting if you squint (sinister receiving), og mark catches you guys, slight angst.
“Since you asked so nicely.” He lifted you up just enough to align his cock to your puckered, twitching hole, rolling his hips upwards just enough to feel the tight ring of muscle start to stretch.
“H- Hhn,” your breath hitched as his dick sunk inside that velvet heat inch by inch.
“Fucking shit..” he suddenly groaned.
You wrap your arms around his shoulders, hiding your face against his neck. You lift your hips and slowly start to bounce on his cock.
“Mmh, Mark..” you moaned, warm breath tickling his skin.
His hips buck upward, meeting your descent with a sharp slap of flesh against flesh. “You feel.. so good. Just like that.”
One of his hands treks down to your ass, gripping it roughly as he uses your flesh to guide your movements—forcing you to take more of his cock with each grind downward.
“N- Nnghh— aah,” you whimper, biting down on his neck.
The squelches and slaps of skin echo through the room, punctuated by your moans and his grunts.
With a sharp gasp, Sinister hilts deep inside you, his cock throbbing as it pumps hot, sticky semen into your ass. You almost yelp, roughly biting down on his flesh to which he yanks you off his lap.
“Ugh..” he clicks his tongue as he drags his fingertips over the deep marks on his neck. “Y’know.. biting is my thing.”
—
Sinister purred when you laid on your back, lifting both your legs up, knees bumping your shoulders—practically folded in half.
He's still rock hard, not a single sign of him softening after his first orgasm. And the new angle allows him to sink even deeper into you.
You feel so incredibly full, stuffed to the brim with his pulsing cock.
He starts to roll his hips, sawing his thick shaft in and out of your stretched, slick hole.
“A- Aahh— Maaark!”
“What would, ngh, your Mark think if he saw you like this?”
“D- Don’t talk about him right now!”
He snickered lowly as angled his hips, hitting your prostate inside dead on.
“Mmmhh—“ You whined loudly, eyes glazed over.
Sinister pulls out slooowly then slams his cock back in with sharp thrusts.
Your noises got louder—panting, gasping, moaning. You weren’t even trying to hide your pleasure.
The creaking of the bed frame fills the room as he fucks into you wildly. His heavy balls slap against your ass with each vicious thrust.
“Aah! U- Uuuf.. ohhh, Mark!!”
You were practically seeing stars—nothing has ever felt this good before. “I- I need to— mmphh, cum.”
You let out shaky pants, eyebrows knitting together in overwhelming sensation, legs starting to shiver. “Fuckfuck…”
Sinister groaned at the sight.
He reaches down with his free hand, finding your dripping erection. He wraps his fingers around it roughly, stroking you in time with his thrusts. His thumb swipes over the sensitive head, smearing the leaking precum around.
“Cum for me. Don’t try to hold it in.”
With a deep, final thrust, he slams into you and grinds against your prostate. His hand squeezes your throbbing cock.
Your entire body seizes up, hole fluttering and clenching around him as you came—cum spurting from your aching dick in thin rivulets.
“S- Shit, Mark!” You practically yelp, looking up at him with the most pathetic eyes he’s ever seen. More pathetic than the many people he’s killed.
He lets your legs down and scoots back a few inches. “You good?”
“Uh, mhm.” You nod, slowly moving to sit up.
“Wait.”
“..What?”
“I want to keep fucking you.”
You blink slowly.
“..Please?” He tilts his head slightly.
You let out a heavy sigh and lay back down.
—
His fingers dig into your hips, pulling you back against him.
He admires the new view—your ass sticking up for him, your back arched, your body slightly trembling in anticipation.
He spits into his palm, rubbing the slickness over his still-hard cock before pressing the thick head against your hole.
“You’re still so tight,” he grunts, pushing forward just enough to make you gasp.
His free hand slides up your spine, gripping the back of your neck as he leans over you. “Your Mark is going to wonder why you’re stumbling around tomorrow.”
With a sharp thrust, he buries himself to the hilt, his hips slapping against your ass with an obscene plop plop plop.
His grip on your neck tightens, forcing you to arch deeper.
“F- Fuck—wait! It feels s-s’good!”
Sinister grins at your words, his thrusts becoming more brutal that your body starts to jolt forward with each time your skin meets with his.
He leans down, his teeth sinking into your shoulder. You let out a sharp whine in response.
Your fucked-out face pressed against a pillow covered in your drool. The pleasure is so deep that it borders on painful, your ass clenches around Sinister’s thrusts until the bed is soaked beneath you, your cum spurting and dribbling from your cock.
You draw out another moan.
He fucks you through your orgasm, pace faltering just a little as he fights his own release.
“Nngh..” He pulls out at the last second, jerking himself off until he spills across your ass and lower back in hot, heavy pulses, the mess sliding down your warm skin. A breathy curse slips from his mouth.
—
The scent of sex and sweat lingers in the air between you, a thick reminder of what just happened.
Sinister huffed as he laid back against pillows, watching as you hooked your bare leg over his hip, your chest almost fully on top of his.
You unconsciously sucked and nibbled at his neck as if it was second nature, your hand firmly holding his jaw on the other side.
He wrapped an arm around your waist and looked down at you with a satisfied, lazy grin, taking in the sight of his cum on the curve of your ass and the small of your back. His other hand treks down to trace through the mess, scooping some up with two fingers and pushing it back inside your fucked hole.
He’s not looking for another round just yet, but he likes the way you cling to him, the way you currently need him.
He shifts slightly, pressing his chest firmer against yours, enjoying the subtle contrast between your body and his. You murmured against the skin of neck and bit down harder when his fingers slipped inside.
“Yeah, that’s it..." he mumbles, his voice thick with post coital content. He can feel how sensitive you've become, the walls of your hole throbbing rhythmically around his fingers.
He slides a third finger in, stretching you wide again, his hand working with a steady kind of grace. He isn't exactly being gentle, but he isn't being brutal anymore either. It’s a slow, possessive kneading.
“Mmm..” you whine quietly.
And suddenly the door slowly opens—
Mark’s voice was soft, like he expected you to be asleep when he walked in.
“I know it’s late and I shouldn’t have broken in, but—”
He cut himself off at the sight of Sinister fingering you.
You were supposed to tell him as soon as you saw the guy. You were supposed to tell him if something was wrong. You were supposed to—
The one thing you weren’t supposed to do was hide the fact you were keeping Sinister at home and fucking him behind Mark’s back.
“..What the hell is this?” Mark stares in disbelief.
Sinister’s body stiffens under you, but he doesn't make an effort to cover you or move away in shame.
Instead, he slowly drags his fingers out of your slick, gaping hole with a wet sound that echoes in the sudden silence.
He looks the doorway, his eyes meeting his own—well, Mark’s wide, horrified gaze. Rather than looking guilty, he looks incredibly annoyed, his brows furrowing as if his intrusion has ruined a perfectly good moment.
“I asked a question.”
Mark’s hands clench into tight fists. His eyes flicker to your nude, sweaty body draped over Sinister’s, then back up to his irritated glare.
He gave Mark a cocky smirk. "What? You caught us post fuck." His voice was lacking even a hint of apology. “Don’t look so shocked, it was bound to happen with me and him.”
“You’re serious.”
It’s not even a question.
Everything that made sense five minutes ago—everything that felt intense, confusing, impossible to untangle—suddenly feels a lot more real under his gaze.
You push yourself up slightly, finally aware of how this looks.
Of what it is.
“…Mark, I—”
“You lied to me.” He cuts you off, sharp.
“I asked you,” he continues, taking a slow step closer. “More than once. If something was wrong. If he came back. And you just—what? Kept him here behind my back!?”
You don’t have an answer. An honest one at least.
His jaw tightens.
“How long has this been going on?”
You’re silent again.
And that’s your answer.
Mark lets out a sharp, disbelieving breath, running a hand through his hair like he’s trying to wake himself up from a bad dream. “This is messed up. This is really messed up.”
You nod hesitantly. “I know.”
“But you still did it.”
Not accusing.
Not even fully angry.
Just hurt.
“I didn’t know how to tell you..”
“You could’ve started with anything,” Mark snaps, the frustration finally coming through. “Instead of—this!”
Sinister sits up slightly, gaze fixed on Mark. “He wasn’t going to tell you.”
You tense up even more. “Stop it—“
Mark’s eyes snap to him. “Don’t speak for him.”
“I don’t have to,” Sinister replies. “He already made his choice.”
“Dude,” Mark says, looking back at you, “this is him. The guy who literally kidnapped you. The guy we’re supposed to be stopping. And you—”
He gestures helplessly, like he can’t even comprehend the thought.
Your chest tightens. “I- It’s.. not that simple.”
That stops him for a moment.
“No, no, you’re right! I get it, you’re choosing him.” Mark spat out sarcastically, disbelief bleeding into every word.
You flinch.
And that says everything it needs to.
Mark laughs once. “Wow.”
Sinister doesn’t look surprised at all. If anything, he looks satisfied, still completely unapologetic. “Told you.”
“I trusted you,” he says.
You swallow, your voice quieter now. “I know.”
“Did you?” Mark asks. “Because it really doesn’t feel like it.”
He takes a few small steps back. Like he needs distance before he says something worse.
“I need a minute,” he mutters, more to himself than either of you, slowly turning around. “We’re talking about this later.”
Then he’s gone.
And the room feels colder without him.
“He’ll come back,” Sinister says. “I would know.”
You’re caught between the person you’ve always known and the one who refuses to let you go.
But no matter what happens next, you’ve already crossed the line.
And there’s no going back from it now.
“…Shit.”
© 𝐬𝐚𝐢𝐧𝐭𝐧𝐨𝐜𝐭𝐢𝐬 — do not copy my work.
