My Billionaire Fiancé Slept With His Adopted Sister

I drove to my fiancé's villa ready to surprise him, but saw him tangled in bed with his own sister.

She wrapped her arms around his neck and giggled. "Doing this with your little sister... isn't that too wicked?"

He answered in a low voice. "A big brother has to take care of his little sister."

---

Two hours earlier, I'd been grinning at my laptop like an idiot.

Two first-class tickets to Cancún. Five days. White sand, no phones, no board meetings. Just me and Adrian Vale, the man I was marrying in June.

I let myself in with the spare key he'd given me last spring. The foyer was quiet, but his car sat in the driveway.

"Adrian?"

No answer.

Then a laugh drifted down the staircase. High and breathy. I knew that laugh.

Sloane.

Adrian's younger sister. Sweet, bubbly Sloane, who called me every week to ask about lipstick shades and boyfriends.

I smiled and started up the stairs. Maybe she'd dropped by to help him plan something for me.

The laugh came again. Then a moan.

My hand froze on the railing.

The bedroom door at the end of the hall stood open a few inches. I moved toward it. Through the gap, I saw them.

Adrian lay on top of her, his bare back slick with sweat, hips driving hard between her spread thighs. Sloane's legs locked around his waist. Her nails dragged down his shoulders.

"Adrian," she gasped. "God, how can you do this to your own sister?"

He shoved into her harder. The headboard banged the wall.

"Because," he panted, "big brothers are supposed to take care of their little sisters."

She laughed against his neck. "Say it again. Call me your sister."

"My sister." He kissed her jaw. "My sweet, filthy little sister."

The tickets in my purse felt like they weighed fifty pounds.

"Mm, Big Brother." Sloane dragged the words out like candy. "Tell me the truth. Is it hotter because you're engaged? Fucking your sister behind your fiancée's back?"

"You know it is."

"And Vivienne has no idea."

"She never will." Adrian rolled onto his back and pulled her on top of him. "Why would she? We're siblings. Nobody suspects siblings."

My fingers dug into the doorframe. The wood bit into my skin.

Sloane straddled him, rocking slowly. "Siblings." She snorted. "We don't share one drop of blood."

"Doesn't matter. Everyone thinks we do."

"Your parents only took me in because Emma died." Her voice turned flat for a second. "I was the replacement. Funny how that worked out."

"Best replacement they ever got." Adrian gripped her hips. "Mom gave you Emma's room, Emma's piano lessons, Emma's spot in the family photos. Nobody's ever going to see you as anything but my sister."

"Exactly. Perfect cover."

She bent down and kissed him, long and wet.

Three years. Three years of Sunday brunches at the Vale estate. Three years of Sloane curling up next to Adrian on the couch.

I'd thought it was cute. I'd thought they were close.

"Remember last summer?" Sloane purred. "When she walked in on us in the wine cellar?"

Adrian chuckled. The sound turned my stomach.

"How could I forget? Her face went completely white."

"I thought we were done for."

"Please." He tucked her hair behind her ear. "All I said was, 'Viv, we're siblings. We've always been affectionate.' And what did she do?"

Sloane burst out laughing. "She apologized! She actually said sorry to us!"

"She hugged you, too."

"She said she felt terrible for thinking something so ugly." Sloane clutched his chest, shaking with giggles. "Oh my God. She's so trusting it's almost sad."

"That's why I picked her." Adrian's hand slid up her stomach. "Old money, good name, and she believes every word I say."

My throat burned. I bit the inside of my cheek until I tasted copper.

Every instinct screamed at me to kick the door open. To grab the lamp off the dresser. To make them feel even a fraction of this.

But what would that get me?

Tears. A scene. Adrian would wrap his arms around me and whisper that I'd misunderstood. Sloane would cry. His mother would call me hysterical. By Monday, the story would be that poor Vivienne had a breakdown.

No.

I pulled out my phone. My hands trembled so badly I nearly dropped it.

I opened the camera, switched to video, and angled the lens through the gap.

Red dot. Recording.

Sloane arched her back and moaned his name. Adrian growled hers. Their faces were perfectly clear in the afternoon light pouring through the window.

Enough.

I stopped recording, backed away from the door, and walked down the stairs without making a sound.

My chest felt hollow. Like someone had scooped everything out and left the shell behind.

I'd just reached the front door when my phone buzzed.

A text. From Sloane.

I stared at the screen.

**Sloane:** Viv!! Emergency!! I have a Valentine's date and I'm torn 😭 red silk or black lace??

A second message popped up before I could breathe.

**Sloane:** You have the BEST taste, future sister-in-law 💕 help me!!

Upstairs, she was still in his bed. Probably still naked. Typing with one hand while Adrian kissed her shoulder.

A laugh slipped out of me. Short and ugly. Then I typed back, the same way I always did.

**Me:** Red silk, obviously. You'll look stunning. 😘

**Me:** Oh, and I'm throwing a party on Valentine's night. You and Adrian HAVE to come. I've got a big surprise planned.

Three dots appeared. Disappeared. Appeared again.

**Sloane:** OMG yes!! We wouldn't miss it! ❤️

*We.*

I slipped out the door and locked it behind me.

In my car, I sat with both hands on the steering wheel for a long time. The villa loomed in the windshield. White columns. Ivy on the walls. The house where I'd pictured raising our kids.

I reached into my purse and pulled out the printed itinerary. Cancún. Two passengers. Mr. Adrian Vale and Ms. Vivienne Marlowe.

I tore it straight down the middle.

Then again. And again, until the pieces fluttered into my lap like confetti.

"You want a Valentine's surprise, Adrian?" I whispered. "I'll give you one."

On Valentine's night, every family that mattered in this city would be standing in my ballroom, every one of them was going to watch.