Cassidy ran until her lungs burned.

Her feet carried her across the pristine lawn, past the tennis courts, through the rose garden, and toward the pond. The night air slapped her face, cold and sharp. Good. Let it hurt. Let something physical distract from the nuclear explosion in her chest.

Fucking Vivienne.

Of course it was Vivienne. Perfect, poised, always-gets-what-she-wants Vivienne. The Valentine heiress with her perfect grades and perfect hair and perfect fucking life.

And Isaiah. Goddamn Isaiah Angelo. The boy who looked at her like she wasn’t broken. The boy who taught her math on graph paper and played tennis with her even though he sucked. The boy who sat in her bed and held her when she couldn’t breathe.

The boy who kissed her sister.

Cassidy reached the wooden dock and collapsed onto it, her knees hitting the weathered planks with a painful thud. She welcomed the sensation. Better than the alternative—the hollow ache spreading through her ribcage like poison.

"Stupid," she whispered to her reflection in the dark water. "So fucking stupid."

She’d thought... what? That she was special to him? That those moments in her bedroom meant something? That when she straddled him and felt his heartbeat under her palm, it was the start of something real?

Cassidy laughed, a harsh sound that scattered a pair of ducks nearby. They flapped away in protest.

"Yeah, run," she told them. "Smart move."

The worst part wasn’t even that he’d kissed Vivienne. It was that Cassidy never saw it coming. She’d prepared for competition with Sabrina—the mysterious one with her books and her secret touches. She’d watched Harlow—the sunshine sister who made everyone fall in love with her just by existing. But Vivienne? Corporate ice queen Vivienne?

"Fuck," Cassidy whispered, then louder: "FUCK!"

The word echoed across the water, bouncing back at her like an accusation.

She’d invited him into her bed. Literally put his hands on her body. Made herself vulnerable when vulnerability meant weakness. And for what? So he could go make out with her sister in some bathroom?

Her phone vibrated in her pocket for the third time. Harlow, probably. Sweet Harlow who followed her outside before Cassidy told her to go back. Harlow who looked just as devastated as Cassidy felt.

At least Harlow had options. She had her cosplay friends and her sunny personality. And Iris absolutely adored her. Even if Isaiah chose someone else, Harlow would still have people who loved her.

Cassidy had tennis. And anger. That was about it.

Sabrina had her silent confidence and those subtle touches Isaiah probably thought nobody noticed. The way she found excuses to sit on his lap or brush against him in hallways.

And Vivienne? Perfect Vivienne had everything. The company. Their mother’s approval. The grades. The future. And now she wanted Isaiah too.

"She can’t have him," Cassidy said to the moon’s reflection. Her voice sounded strange to her own ears—hoarse and raw, but certain. "She can’t just take everything."

Cassidy pulled her knees to her chest and tried to sort through the hurricane in her head. What did she even have to offer compared to her sisters?

She wasn’t mysterious or smart like Sabrina. She wasn’t warm and loving like Harlow. She wasn’t successful and put-together like Vivienne.

She was just... Cassidy. Loud, angry, failing-her-classes Cassidy. The problem child. The one who broke things. The one people tolerated rather than chose.

Why would Isaiah pick her when he had her sisters as options?

The obvious answer made her stomach twist: he wouldn’t.

But then... he hadn’t pushed her away in her bedroom. He hadn’t seemed disgusted when she straddled him. His hands had stayed on her waist, warm and steady, his eyes dark as they looked up at her. When she’d shifted her hips against his, she’d felt his reaction. 𝙧𝙚𝙚𝔀𝒆𝓫𝓷𝙤𝓿𝒆𝙡.𝒄𝙤𝓶

That wasn’t faked.

And before that—on the tennis court, in the library, during their lessons—there were moments. Small ones. The way his eyes followed her. The patient explanations. The belief in her when she couldn’t believe in herself.

"Maybe," she whispered, "maybe it’s not over."

Cassidy stood up, her legs steadier than before. The initial shock was wearing off, leaving something else in its place. Something that felt like resolve.

She might not be the smartest Valentine. Or the sweetest. Or the most accomplished. But she had one advantage none of her sisters had:

she didn’t give a fuck about playing fair.

Vivienne wanted a competition? Fine. Cassidy would give her one.

Walking back toward the house, Cassidy scrolled through her phone, past Harlow’s worried texts, to the one that mattered: the picture of her math test with the big red 62% circled at the top. Not passing. Not even close.

That meant their bet was still active. The Pet Bet, where if she failed to get a B, she’d be Isaiah’s pet for a day. Do whatever he wanted. Even wear a collar if he asked nicely.

She’d meant it to scare him off when they first made the deal. A way to shock the prim scholarship boy with her crudeness.

Now it was her secret weapon.

Let Vivienne have her fancy gala kisses. Cassidy would have Isaiah for a full day, at her mercy—or her at his. Either way, she’d make sure he never thought about Vivienne once during those twenty-four hours.

By the time she reached the east wing, Cassidy had a plan. Not a good one. Not a smart one. But a plan.

Operation Make Isaiah Mine was officially a go.

She paused outside his guest room door, hearing low voices inside. Her blood froze. Was Vivienne in there? Had she gone running to him the moment Cassidy left?

Cassidy pressed her ear against the door, shameless in her spying.

"...talking about which sister really kissed you on the steps." Sabrina’s voice, soft but clear.

Cassidy’s eyes widened. What the actual fuck? Someone had already kissed Isaiah before tonight? And it wasn’t Vivienne?

She pulled away from the door, mind racing. She couldn’t barge in now—it would be too obvious she’d been eavesdropping. And whatever Sabrina was talking about, it was something none of them knew.

Cassidy retreated to her room, locked the door, and fell onto her bed.

First, someone had kissed Isaiah on the steps, and it wasn’t Vivienne.

Second, Sabrina knew about it.

Third, Vivienne and Isaiah were now apparently a thing.

Fourth, Cassidy was not going to accept that without a fight.

She stared at her ceiling, plans forming and discarding in her mind. The Pet Bet was a good start, but she needed more. She needed to make Isaiah see that Vivienne wasn’t his only option. That Cassidy Valentine was right here, wanting him with an intensity that scared even herself.

Her phone lit up with another text. Not Harlow this time.

Isaiah: Are you okay?

Three simple words that made her heart stutter.

She considered ignoring it. Considered telling him to fuck off. Considered something crude and dismissive.

Instead, she wrote back:

No. But I will be. Get some sleep, tutor boy. We still have a bet to finish.