My Brother's Best Friend, My Secret F1 Lover

Sienna's POV

The AC in the bridal suite was set to arctic, and the only thing within reach was the black jacket I'd stolen four hours ago.

So I put it on. Over the sage-green dress. Like an idiot.

Across the room, Olivia sat at the vanity while a makeup artist dabbed highlighter on her cheekbones. She caught my eye in the mirror and raised one perfect brow.

"That's not yours."

"It's a loaner."

"From who?"

Before I could invent an answer, the door swung open and my brother walked in, tie half-knotted, holding a bouquet of white garden roses like it might detonate.

"Liv, the florist says these are yours, and I'm not allowed to see you, so I'm going to stare at the wall." Then Noah stopped. His eyes landed on me and narrowed. "Where were you last night?"

"Sleeping."

"Where?"

"In a bed, Noah. That's where people usually sleep."

He set the bouquet down and walked over, tugging the lapel of the jacket between two fingers. "This is a men's jacket."

"The hotel had a lost and found. I was cold." I shrugged. "They let me borrow it."

"The hotel let you borrow a three-thousand-dollar Italian jacket."

"It's a very nice hotel."

I shoved my hands into the pockets to look casual, and my fingers closed around something small and cold. I pulled it out before I could stop myself.

A silver cufflink. Engraved with a tiny number seven.

Noah looked at it. Then at me.

I closed my fist. "Also borrowed."

He sighed the way he'd been sighing at me since I was twelve, then reached for the bridesmaid brooch pinned crooked on my strap and straightened it, his knuckles brushing my collarbone. Gentle, even while he was annoyed.

"Today matters to me," he said quietly. "So please. Be normal. And stay away from my friends, Sienna. Especially the drivers."

"I'm twenty-seven."

"I'm aware."

"So why am I still getting the rules you gave me at fifteen?"

"Because at fifteen you kissed my lab partner, and at twenty-two you dated my roommate, and he cried on my couch for a month." He tapped the brooch. "Jacket off. Ceremony in twenty."

He walked out. Olivia was biting her lip to keep from laughing.

I slipped the cufflink into my clutch and told myself I'd mail it to the hotel.

Anonymously.

---

The ceremony was on the cliff terrace, white chairs lined up facing the Mediterranean. My job was to walk Olivia's niece, Lucy, down the aisle without letting her eat the petals.

"Slow," I whispered, squeezing her sticky hand.

"I *am* slow."

White gauze hung from the wedding arch, and the sea wind kept lifting it into the air like a sail. Noah stood beneath it, grinning like a kid. Next to him, his back to the aisle, stood a tall man in a navy suit.

Broad shoulders. Dark hair curling slightly at the nape.

My heels slowed on their own.

Lucy tugged my hand. "Aunt Sienna, *walk*."

The man turned around.

Kai.

Freshly shaved, in a different suit, since the other one was currently in my suitcase. His gaze moved over my face, then slid, slowly, down to my left shoulder, right where his mouth had been last night.

The ring box in his hand tilted. Noah caught it before it hit the ground.

"Dude. Hands."

"Sorry," Kai said, still looking at me. "Got distracted."

I made it to my spot somehow. After the vows, after the kiss and the cheering and Olivia sobbing mascara onto Noah's lapel, my brother threw an arm around Kai's shoulders and steered him straight to me.

"Sienna, this is Kai Mercer. My best friend."

Kai held out his hand. "Sienna."

He said it like he was tasting it. Like he was filing away that it wasn't Nora, the name I'd given him at the bar.

I shook his hand. Firm, quick. "Nice to meet you."

"Is it?" he said.

---

The photographer wanted the full wedding party, and of course I ended up beside the best man.

"Closer, closer," she called, waving us in. "Bridesmaid, lean toward the gentleman."

I leaned approximately one inch.

Kai bent his head, his voice low enough that only I could hear. "So. Do you always take everything a man owns, or was I special?"

"Smile for the camera."

"I had to leave that hotel in a bathrobe, Sienna. Security walked me to my car."

"Sounds like a you problem."

The flash went off. I kept my teeth showing.

"You owe me a suit, Sienna."

"You owe me your silence," I said through my smile. "Last night doesn't exist. Not to him, not to anyone. Say one word and I'll tell the press you cry during rom-coms."

"I do cry during rom-coms."

"Then I'll make it worse."

"Tighter!" the photographer called. "Sir, put your hand on her back."

His palm settled at the base of my spine, warm through the thin silk. Exactly where it had been on the sofa, before the zipper tore. My whole body remembered before my brain could stop it.

The flash fired again. His thumb moved, barely.

"By the way," he murmured, "I'm missing a cufflink."

"Okay, that's enough." Noah appeared out of nowhere and wedged himself between us, one hand on each of our shoulders. "Let's get one with the groom in the middle. Groom loves the middle."

The photographer shrugged and kept shooting.

Noah turned his head toward Kai, still smiling for the lens, and spoke under his breath. "That's my sister, man. She's not some girl at the paddock party you get to chat up."

Kai's smile didn't change. "Understood."

But when Noah looked away, Kai's eyes found mine over his shoulder.

He didn't look understood at all.

---

Dinner was served under strings of lights, the band playing something soft and French. I waited until Noah was trapped in a conversation with Olivia's grandmother, then cornered Kai by the bar.

"Here." I pressed the cufflink into his palm. "Take it. We're even."

He looked down at it, then closed my fingers back around it. His hand stayed over mine.

"Even? You've got my shirt, my pants, my jacket, my belt, and my favorite cap." He tilted his head. "So maybe we talk about compensation. Tonight."

"There's nothing to talk about. Last night was an accident."

"An accident."

"A one-time, never-happening-again accident."

He stepped closer. He smelled like cedar and something sharper underneath, the expensive cologne his sponsor probably paid him to wear. His mouth came close to my ear.

"Funny," he said. "You weren't this cold last night. Last night you were pulling me by my tie and telling me not to stop."

My face went hot. "Keep your voice down."

"Why? Afraid someone will hear?"

"What are you two whispering about?"

I spun around. Noah stood right behind us, a glass of red wine in his hand, his smile a little too pleasant.

Kai didn't move away. He just leaned back against the bar, completely relaxed, and looked at me with those dark, amused eyes.

"Go ahead," he said softly. "Tell your brother how we met. I dare you."

Noah's gaze went from Kai to me. "Met?"

My hand jerked. The cufflink slipped from my fingers, hit the rim of the champagne flute I was holding, and dropped straight in.

It sank through the bubbles and landed at the bottom with a tiny clink.

Silver. Engraved with a seven.

Noah looked down at the glass.

Then, very slowly, he looked at Kai's bare left cuff.