The rest of the day blurred into a haze of skin, sweat, and whispered filth.

After the couch, we barely left each other’s orbit. Mia dragged me to the shower again—not to clean up, but to pin me against the tiles while she rode me standing, water pounding our shoulders, her nails carving crescents into my back as she came twice more before I filled her a fifth time that day. We ate lunch naked at the kitchen counter—her sitting on my lap, my cock still half-hard inside her while she fed me bites of sandwich between slow, grinding rolls of her hips.

By late afternoon, the apartment reeked of sex. Sheets stripped and abandoned on the floor. Towels discarded. Every surface we’d touched bore some evidence: faint handprints on the mirror, sticky spots on the couch, her bite mark blooming purple on my shoulder.

We ended up in my bedroom—our bedroom now, unspoken. She pushed me onto my back and straddled my face without preamble.

“Eat me,” she ordered, voice rough from moaning all day. “Taste how full you’ve kept me.”

I obeyed.

Her thighs clamped around my head as she ground down, smearing our mixed release across my tongue. Salty, sweet, thick. I licked deeper—sucking her clit, tongue-fucking her until she trembled and flooded my mouth again. She came shaking, fingers twisted in my hair, grinding so hard I could barely breathe.

When she finally lifted off, her pussy was swollen, glistening, dripping onto my chin.

She slid down my body, positioned herself over my cock—still impossibly hard, veins throbbing, slick from her—and sank down in one smooth drop.

“God,” she hissed, head thrown back. “How are you still this hard? After all that?”

“Because it’s you,” I groaned, hands gripping her hips.

She started riding—slow, deep, deliberate. Rolling her hips in figure-eights that made me see stars. Her breasts bounced gently; I caught one in my mouth, sucking hard on the nipple until she whimpered.

“Look at me,” she demanded.

I did.

Her eyes were dark, pupils blown, cheeks flushed. Sweat beaded between her breasts and trickled down her stomach.

“I want you to say it,” she breathed. “Out loud. While I fuck you. Say who owns this cock.”

“You do,” I rasped. “My sister owns my cock. No one else gets it hard. No one else gets it wet. No one else gets to come inside you. Only you. Forever.”

Mia’s rhythm faltered for a second—her walls fluttering around me like she was close again.

“Say you’ll never touch another girl,” she pressed. “Swear it.”

“I swear,” I said, thrusting up hard to punctuate it. “I’ll never look at another pussy. Never get hard for anyone but you. If I even think about it, I’ll come straight to you. Beg you to fix it. Use your mouth, your tits, your cunt—whatever you want. Just to prove it’s still only yours.”

She moaned, loud and broken. “Fuck—yes. That’s my good boy.”

The words hit like lightning. I flipped us again—her under me now, legs hooked over my elbows, folded nearly in half. I drove into her with everything left—deep, brutal strokes that made the headboard slam against the wall.

“Harder,” she begged. “Fuck me like you’re claiming me. Like you’re marking me so deep no one else could ever reach.”

I did.

Pounded until her voice cracked on every thrust. Until her nails raked bloody trails down my back. Until she came again—screaming my name, pussy spasming so violently it dragged me over the edge with her.

I buried myself to the hilt and came—long, aching pulses that seemed to go on forever. Filling her until it leaked out around my cock, pooling on the sheets beneath us.

We collapsed, tangled, and wrecked.

For a long time, neither of us spoke. Just breathing. Hearts hammering against each other.

Eventually, Mia traced the fresh scratches on my back with gentle fingertips.

“Tomorrow,” she whispered. “We go back to normal. Work. College. People. But this…” She clenched around my softening cock, still inside her. “This doesn’t stop. You come home to me. Hard. Needy. Only for me. And I’ll take care of it. Every time.”

I kissed her temple. “Every time.”

She smiled against my chest—small, satisfied, possessive.

“And if anyone ever tries to take you from me…” Her voice dropped, edged with something darker, hotter. “I’ll remind them—and you—exactly who you belong to.”

I shivered. Not from cold.

Months passed like a fever dream we never wanted to wake from.

We learned the rhythm of secrecy the way siblings learn each other’s habits—quiet, instinctive, unbreakable. Mornings started with her slipping into my bed before the alarm, straddling me while the city outside was still half-asleep, riding me slow and silent until we both shuddered through muffled climaxes. Evenings ended the same way: her crawling under the covers after her shower, whispering “prove it again” against my throat while I hardened instantly at the scent of her skin.

No one suspected.

Our parents visited once—stayed three days—and we played the perfect siblings. Polite distance. Shared jokes. Separate rooms. But the second their bedroom door clicked shut each night, Mia would text me from across the hall: *Door’s unlocked. Come fill what’s yours.*

I’d wait ten agonizing minutes, then pad barefoot through the dark apartment, slide into her narrow college bed, and fuck her with my hand clamped over her mouth so the headboard wouldn’t betray us. She came hardest those nights—clenching so violently I had to bite her shoulder to keep from groaning loud enough to wake the house.

Work and college dragged us apart during the day, but the rule held ironclad:

No other girls.

No porn that didn’t star someone who looked vaguely like her.

No excuses.

If a coworker flirted too hard, or an old hookup texted out of the blue, I showed Mia the message immediately. She’d read it, smirk, then drop to her knees right there in the living room or kitchen or hallway—wherever we were—and suck me until I forgot the other woman’s name ever existed.

She marked me in ways no one else would ever see:

Small hickeys hidden under shirt collars.

Light scratches that stung pleasantly under the shower spray.

Once, after a particularly jealous day, she bit the inside of my thigh hard enough to bruise while she rode me reverse-cowgirl, whispering, “This stays between us. Forever.”

And I marked her right back.

Faint fingerprints on her hips.

A necklace of bite marks across her collarbone that she covered with makeup for class.

My cum leaking out of her when she left the apartment—sometimes still warm, tucked inside panties she refused to change until she got home so she could “feel me all day.”

The exclusivity became religion.

One humid Saturday night—six months after that first confession on the couch—Mia came home late from a study group. I was on the sofa pretending to watch a game when she walked in, cheeks flushed, hair mussed from Manila traffic and laughter.

She dropped her bag, kicked off her shoes, and straddled my lap without a word. Her skirt rode up; no panties underneath. She was already soaked.

“Some guy in my group kept staring,” she murmured, grinding down until my cock—already straining at the sight of her—notched against her entrance. “Tried to ask for my number. I told him I have someone. Someone who gets rock-hard the second I walk in the room. Someone who can’t even think about anyone else.”

She sank down slowly, taking every inch with a sigh that sounded like coming home.

I gripped her waist. “And?”

“And he didn’t believe me.” She rolled her hips in that devastating circle she knew destroyed me. “So I thought about you the whole ride home. Thought about coming back here and letting you fuck the memory of him right out of me.”

I thrust up hard—once, twice—making her gasp.

“Then let me,” I growled. “Let me remind you who you belong to.”

We fucked like it was the first time all over again.

Clothes half-on, desperate.

Her on top, then me flipping her onto the cushions, legs over my shoulders, pounding so deep she left crescent-moon indents in my forearms.

She came screaming—voice raw, body shaking—then begged for my mouth while I was still inside her. I pulled out just long enough to drop between her thighs and lick her through another orgasm, tasting myself leaking out of her, before sliding back in and finishing with long, grinding strokes that made us both see white.

Afterward, we lay tangled on the couch, her head on my chest, my fingers tracing lazy patterns on her spine.

“Think we’ll ever get tired of this?” she asked quietly.

I kissed the top of her head. “No. Because even if the world found out… even if everything went to hell… I’d still only get hard for you.”

She lifted her face, eyes shining in the dim light.

“Promise?”

I cupped her cheek. “I swear on every failed date, every doctor’s appointment, every night I jerked off alone thinking of you. It’s always been only you. It always will be.”

Mia smiled—small, real, possessive—and kissed me slowly.

“Then we keep going,” she whispered. “Just like this. Brother and sister on the outside. Everything else behind closed doors.”

I pulled her closer.

“Everything else,” I agreed.

And we did.

We still do.

Only for her.

The End