My Brother's Best Friend, My Secret F1 Lover

Sienna's POV

The cufflink spent the first dance at the bottom of my champagne flute.

Olivia had dragged Noah onto the floor two seconds before he could finish his question, and I'd escaped with the glass like a thief carrying evidence out of a crime scene. In the bridal suite, I fished the cufflink out with two fingers, dried it on a tissue, and wrapped it in my fist.

Then I opened the door and walked straight into Kai.

He was leaning against the hallway wall, scrolling through his phone. His jacket hung open, and his left cuff flapped loose where the missing cufflink should have been.

"Perfect timing," he said, and turned the screen toward me.

It was an email from the hotel. *Dear Mr. Mercer, we sincerely apologize for this morning's misunderstanding on the twenty-third floor. Our security team has confirmed there was no harassment of any guest...*

"They're comping my suite for the rest of the month," he said. "Apparently, nearly arresting a championship contender is bad for business."

"Congratulations."

"Thank you. I had to describe your stolen outfit to three different managers."

Down the hall, Noah's laugh carried out of the ballroom. I glanced toward it. Nobody was watching.

That's when I noticed the clear garment bag folded over Kai's arm. A flash of red silk showed through the plastic. My dress. The broken zipper sat right on top, exactly where I'd left it.

I reached out and touched the bag before I could stop myself.

"You kept it?"

He shifted the bag out of my reach and tucked the loose edge of plastic back in place.

"You stole my clothes and almost got me arrested. At least let me keep the evidence." He tilted his head. "Be honest. Did you plan to humiliate me? Is there a rival team paying you?"

"Yes. I'm a very expensive corporate spy."

He laughed, low and easy, and something in my chest tugged hard.

Last night, before anything happened, he'd stopped with his hand on my cheek and asked if I was sure. No smirk, no line. Just a real question, waiting for a real answer.

I didn't like how clearly I remembered that.

"I need to get Olivia's bouquet," I said, and walked past him.

---

The bouquet was waiting on a side table by the terrace doors, wrapped in ivory satin ribbon. Next to it sat a crumpled printout of the old wedding schedule, the version Noah had made before Olivia vetoed his idea of a forty-minute slideshow.

The terrace door was half open. I reached for the flowers and heard my brother's voice.

"I'm serious, man. Don't flirt with her. Not tonight, not ever."

"I was being polite," Kai said.

"You were standing four inches from her at the bar."

"Noah. Why are you so wound up about this?"

There was a pause. Through the gap in the door, I could see Noah's hand resting on the railing, his new wedding ring catching the string lights.

"A few years ago, a guy I knew humiliated her," Noah said quietly. "One of my friends. I brought him around, and he made her a joke in front of a lot of people. She pretended it didn't matter." He exhaled. "It mattered."

My fingers curled around the satin ribbon until it creased.

I remembered Noah sitting on the edge of my bed that night, still in his jacket, saying, *I won't let any friend of mine hurt you again. I promise.*

I'd loved him for it then.

Now I was twenty-seven, and he was still guarding my door.

"She is off-limits, Kai."

I pushed the door open.

Both of them stopped talking at once. Noah straightened so fast he nearly knocked his wine off the railing.

"Sienna. Hey."

"Hey." I held up the bouquet, ribbon crushed in my fist. "Don't stop on my account. You were just getting to the part where I'm fragile."

"That's not what I said."

"I'm twenty-seven, Noah. Not seven."

His jaw worked. For a second, he looked hurt, and I hated that I could tell.

"I know how old you are," he said.

From inside, Olivia's voice called his name. Cake cutting. He looked at me, then at Kai, then back at me.

"Five minutes," he said, and went inside.

---

The terrace went quiet except for the band and the sea.

I opened my palm and held out the cufflink.

"Dried it myself. You're welcome."

Kai took it, his fingers brushing mine. "It's still damp."

"It went for a swim. So did your dignity this morning." I leaned against the railing. The metal was cold through my dress. "How long did security keep you? Did they make you hold the towel with both hands?"

"One hand. The other one was holding your dress."

"The housekeeper will be telling that story at Christmas for twenty years."

"She asked for a selfie once they cleared it up."

I laughed. He pushed back his sleeve to put the cufflink in, and I saw a faded gray fabric band around his wrist, frayed at one edge, the letters almost rubbed off.

"What's that?"

He looked at it for a moment. Then he turned his arm over. A long, pale scar ran from his wrist halfway to his elbow.

"Crash at Suzuka, five years ago. Broke my arm in three places. Doctors said I might not grip a steering wheel properly again." He touched the band. "Your brother gave me this the day I walked out of rehab. Showed up at six every morning for four months and made me squeeze tennis balls until I wanted to murder him."

"Noah did that?"

"Noah did that." He smiled a little. "He's the reason I'm still racing."

The joke went out of me. I looked at the scar, then at the band, and suddenly the man in front of me wasn't just a cocky driver I'd stolen pants from. He was someone my brother had carried when he couldn't stand.

"Are you afraid of my brother?" I asked.

Kai fastened the cufflink and didn't look up.

"I'm more afraid of breaking a promise to him."

Then he took a step back. Just one, but it felt like a line being drawn on the terrace floor.

"After the wedding," he said, "we should probably just stop this. Whatever it is."

It was the right answer. It still landed like a slap.

I reached up and straightened his tie, because it was crooked and because I needed something to do with my hands. The silk was smooth and warm from his skin.

"Relax," I said. "Once was enough."

"Good."

"It was an accident anyway."

"You've mentioned."

I let go of his tie and turned toward the ballroom. The texture of the fabric still clung to my fingertips.

My phone buzzed in my clutch.

Jules. *CONTRACT SIGNED!! Vesper Racing approved the crew. You're shadowing their lead engineer, Mara Ortiz, all season. Full team roster attached. Call me!!!*

I opened the attachment. The documentary contract came first, my signature already on it. Then the team roster.

The first page had a photo. Dark hair, cocky grin, racing suit unzipped to the waist.

*Driver: Kai Mercer.*

I stopped walking. Slowly, I turned around and held up my phone.

Kai glanced at the screen.

His smile froze.

"Then why," he said quietly, "are you on my team's filming schedule?"