My sister always prided herself on her self-control. Even after six years of dating, she still insisted she was untouched.

One day, I noticed something strange–her tongue was covered in metal piercings.

That was when I realized… she had been using a different way all along.

When I confronted her, she only smirked.

"This way, men enjoy it more–and they become obsessed precisely because they can't have me. You wouldn't understand."

However, looking at the damage already spreading through her mouth, I could not stay silent. I told her the risks–disease, even cancer–and that men obsessed with that kind of "purity" weren't good people to begin with.

She did not listen.

That very night, she gave herself to a powerful heir.

Later, when the woman he truly loved returned, he discarded her without hesitation.

She laughed it off, calling him a scumbag.

However, on my birthday, she hid a knife inside a cake–and slammed it into my face.

As the blade pierced through me, she burst into laughter.

"If you hadn't pushed me to give it away, why would he stop valuing me? Why would he leave me?

"This is all your fault. You deserve to die."

When I opened my eyes again–

I was back to the day I first saw the piercings on her tongue.

"Penny, what century are you living in? Why are you still so old-fashioned?"

I jolted awake.

My older sister Nina Sterling was leaning over me with her tongue sticking out, wagging it back and forth in front of my face. The whole length of it was studded.

A chill ran through me. "What are you doing?"

Looking at her, all I could think about was the knife she had once driven into my face. Instinctively, I took a step back.

Seeing my reaction, she laughed. She stepped closer, grabbed my hand, and pressed my fingertip against her tongue.

"Well? Feels textured, doesn't it?"

She licked the corner of her lips, her eyes full of provocation. "You don't even know how much Marcus loves it."

"All these years, he's had countless women around him. But I'm the only one he's publicly acknowledged as his girlfriend."

The damp, uneven sensation under my fingertip was real. Revolting.

So… I really had come back.

I forced down the nausea and played along. "You really are something."

She lifted her chin proudly. "Of course. Otherwise, why would the Mercer family specifically ask for me in the marriage arrangement?"

I nodded. "The Mercer family is well-known in high society. Once you marry into them, don't forget about me."

She let out a short laugh and tapped my shoulder.

"It's not like I didn't try to refuse the match. But what can I do? Marcus Mercer just can't get enough of me."

"You can be the real Sterling daughter all you want, what's yours still ended up in my hands."

I smiled.

The reason she was so confident was simple.

A year ago, I had been found and brought back to the Sterling family–their real daughter.

As for her, she was only the foster child my family had taken in after I went missing.

A year ago, when the Mercers came to propose the marriage, the one they originally wanted… was me.

Mr. Mercer admitted I was not as polished as Nina, but at least I carried the Sterling family's blood.

I looked at Marcus. He was handsome. He did not object.

At the time, I thought–after finally finding my biological parents, and now with this marriage–things were finally turning in my favor.

So I agreed, full of hope.

What I did not expect was that after dinner, sounds would come from Nina's room–loud enough for almost the entire house to hear.

She was not my father's biological daughter, but he had always doted on her.

Thinking something was wrong, he forced the door open–and saw her, clothes disheveled, draped across Marcus.

He was furious. He slapped her on the spot.

"This is outrageous! He's your sister's fiance!"

Vivian Sterling, my stepmother, immediately stepped in front of her. "How is this Nina's fault? Nina is gorgeous. Everyone had been drinking. They're young, you know how it..."

Nina suddenly dropped to her knees in front of me, tears streaming down her face as she slapped herself.

"I didn't mean to, I swear!

"I… I drank what you gave me. I wasn't thinking clearly…

"No–I was wrong. Please, don't make me leave…"

My father looked at me, disbelief written all over his face. "Penny, sweetheart..."

I was about to explain that I had not done anything–but Marcus let out a light laugh and pulled Nina to her feet.

"They're both daughters of the Sterling family. It makes no difference to me.

"Nina has the better image. She's more suitable."

With that, there was nothing my father could do.

I left, shaking with anger, slamming the door behind me.

A few days later, I forced myself to swallow it.

I told myself Nina had lived as the eldest daughter of this family for years–of course she felt insecure. And Marcus, agreeing to marry me one moment, betraying me the next. It was not worth holding onto.

One day, as I passed by Nina's room, I overheard Vivian speaking.

"Listen carefully. Marcus gets bored easily. If you give in too quickly, he'll lose interest."

Nina laughed. "Don't worry, Mom. I've been with him for six years… and I am still a virgin. I have my methods."

I had been confused about that line, until the day I caught her in front of the bathroom mirror, counting the steel beads in her own tongue.

That was when I figured out what her method was.

Old me, decent person that she was, had actually warned her. "Doing that long-term isn't good for your health. And this is a marriage alliance–you can't just back out. You should take better care of yourself."

She thought about it, misunderstood what I meant, and that very night, she gave herself to Marcus.

What I had not seen coming was that, when Marcus's first love came home from overseas, he would walk away from Nina without a backward glance.

And in the end, she blamed everything on me.

The thought of it made my cheek throb where the knife had gone in.

I forced myself to stay calm and asked, as if surprised, "But you've heard the rumors, right? About Marcus and the woman he can't forget?"

She nudged me, completely confident. "So what? The thing men love most in this life is the thing they can't have."

"As long as I keep doing what I'm doing with my mouth, he keeps fantasizing. No first love, no nothing, can pull him out of that."

Seeing how confident she was, I felt a flicker of satisfaction.

In my previous life, I had been able to move on from this arranged marriage so quickly for a reason–I had someone investigate Marcus.

It didn't take long to find out what kind of person he was.

A regular at private rooms in clubs. Seven nights a week, surrounded by women.

What kind of problems he might be carrying–no one could say. He had to be a walking petri dish.

And Nina, knowing that, was sitting on cloud nine because she'd figured out how to please him with her mouth.

I made a show of glancing at my phone. "Look, don't take this the wrong way. Since I'm the PR director at Sterling Group, after the merger was announced, I had someone keep an eye on Marcus."

She frowned. "Stop bringing up your PR job. Just say what you want."

I handed her the phone. "I'm just concerned about the family's reputation."

She snatched it from me. The moment she saw it, her expression changed.

The screen showed Marcus going in and out of clubs, a different woman in his arms each time.

She tossed the phone back to me, quickly fixing her lipstick.

"I'm heading out. Cover for me with Mom and Dad. Tell them I went to bed early."

My dad was not a prude, but he had a thing about clubs. He thought decent young women did not belong in places like that.

Especially not Sterling daughters. The family name was on the line.

I nodded. "Alright. Just make sure you keep Marcus under control."

She bristled. "Don't think I don't see what you're doing. Pitting him and me against each other so you can slide back in. Not happening."

She stalked out in her heels.

She did not come back that night.

The next morning, she showed up at breakfast wearing a mask.

My dad gave her a look. "What's going on, sweetheart? Take that off and eat."

She avoided his gaze, her voice slightly off. "I think I caught a cold. I'll skip breakfast–I don't want to pass it to you."

I almost laughed out loud. She had been with Marcus all night, and her mouth was wrecked.

Vivian hurried over and helped her sit down. "Did you get cold last night? I had ginger tea sent up to you."

Nina looked across the table at me. "I gave it to Penny. She wanted some."

Vivian whipped her head around. "Penny, what's wrong with you? You know your sister isn't in good health. I made that tea specially for her, and you still took it?"

She caught the way my dad's eyebrows lowered, and softened her voice. "I'm just saying, if you wanted some, I would have made you your own. There's no need to take hers."

"Besides, she's marrying into the Mercer family in a month. She can't afford to get sick."

Nina, of all people, jumped to my defense. "Mom. Penny didn't mean any harm. Stop, please."

Then she turned to me, her tone gentle again. "Penny, you're in PR. Come look at these wedding dresses with me. Tell me which one suits me best."

I had no idea what she was up to, but I followed her up.

The moment we stepped inside, she yanked off her mask. A foul, rotting smell hit me immediately. Her mouth was covered in angry red sores–disgusting to look at.

I forced a concerned tone. "What happened to you?"

She tossed the mask aside. "The piercings got infected. You used to be a doctor. Take a look."

I hesitated.

She suddenly grabbed a knife and pressed it against her face, her voice turning hysterical. "Hurry up! Or I'll tell Mom and Dad you've been bullying me!"

That trick of hers had a hundred percent hit rate.

She might be a foster, but after fifteen years my dad treated her like blood. He defended her on autopilot.

Just earlier, even though I was clearly the one wronged, he had not said a word.

I let out a quiet sigh. "Fine. Put the knife down. Looks like the friction is too much. The implant sites are tearing."

"I'll go to the pharmacy and get you something to ease it for now."

She smiled, smug. "By the way. Since you've been keeping tabs on Marcus, the second you spot anything off, you tell me."

"Once I'm officially Mrs. Mercer, I'll put in a word with Mr. Mercer about you. Marcus has a cousin. The lame one. Edward. You'll be set up with him."

"Don't act like that's beneath you. He's a Mercer. Without me, you don't get within a mile of that family in this lifetime."

I made a noncommittal sound and walked out.

On my way to the pharmacy, my assistant called.

"Ms. Sterling, there's an update on Whitney Bell."

I pulled up the date. Right on schedule. Marcus's first love Whitney Bell, was flying in. Her flight would land in less than thirty minutes.

I went to the pharmacy, then quickly headed back. I swapped a few vitamin tablets into an antibiotic box and handed it to Nina.

She saw me hesitating and kicked me, annoyed. "I hate it when you act like this. If you have something to say, just say it."

I drew a slow breath. "Marcus's first love is back in town. They're meeting at the Royale Hotel, room 7032."

Her expression changed instantly.

She yanked the mask back over her mouth and stormed out, fury in every step. "First love? She dares to seduce my fiance? Let's see how far she gets."

She let out a cold laugh. "Imagine her face when she watches Marcus undone in front of me. That's going to wreck her."

After she left, I finally relaxed.

An hour later, the Mercer family came calling. The first words out of their mouths were that they were canceling the engagement.

Vivian's face turned red with anger. "What is the meaning of this. Are the Mercers playing games with my Nina?"

I took my time and produced photos my surveillance team had gotten at the airport. "Half an hour ago, my sister went chasing after Marcus. Cheating allegation. Royale Hotel, room 7032."

Vivian saw the photos and slapped me hard across the face. "Why didn't you say something earlier?!"

"The nerve of that woman–trying to seduce my daughter's fiance! Get people there now! I want her dragged out of that hotel!"

My dad was banging the table. "Go now! Calling off the engagement is one thing–Nina getting hurt is another!"

He paused, then turned to me. "Penny, you know people in the media. Call them. If the Mercer family tries anything, I want their reputation destroyed by tomorrow."

I gave him a docile little nod.

The whole convoy roared up to the front of the Royale, and we marched up to room 7032.

From inside came unmistakable, explicit sounds.

Vivian clutched at her chest. "She's heartbroken in there. I will not let him get away with this."

On her order, security kicked the door in. I lunged in first and slapped the lights on.

The whole room went still. Vivian sank to the floor.

"Nina… what are you doing?!"