My parents made me and my sister take turns being their only daughter, Sophie, every month, while the other had to live in the basement and pretend she didn’t exist. When I got sick during an off month and started vomiting blood, they gave us seven days to decide which sister they’d kill with pills so they could finally have just one daughter.

But we tricked them into thinking we’d both been poisoned and escaped while they panicked. My parents said they could only have one daughter, and they meant it. My parents made me and my sister swap identities every month because they said only one daughter deserved to exist at a time, and we had to take turns being the real child while the other became invisible.

My parents always said they’d only wanted one daughter. When my sister Scarlet was born 11 months after me, they treated it like a cosmic mistake that needed correcting. They couldn’t afford to raise two children, they said. But more importantly, they didn’t have enough love for two daughters. Lucky for them, we looked nearly identical. Same dark hair, same green eyes, same small frame.

So, they created a system. One month, I was their daughter, Sophie. The next month, I had to pretend I didn’t exist, while Scarlet became Sophie. The outside world never knew there were two of us. The switching ceremony happened at midnight on the first of each month. Scarlet and I would stand in the living room while our parents formally transferred their recognition from one daughter to the other. The girl whose turn it was ending had to hand over everything—her bedroom, her clothes, her name, even her school assignments.

Mom would kiss the leaving daughter on the forehead and say, “See you next month, stranger.” While dad removed her from existence entirely. The non-existent daughter moved to the basement with a sleeping bag and was forbidden from appearing anywhere. During Scarlet’s months, I had to coach her through phone calls on how to be me—my teacher’s names, my friends’ birthdays, my class schedule. During my months, she did the same. We shared one school record, one medical file, one life split between two girls. Everyone thought Sophie was just moody, never realizing she was actually two different people.

Living as half a person, each bonded Scarlet and me in the most twisted way. During my off months in the basement, she’d sneak down after our parents slept, and we’d whisper through the darkness. She’d tell me what happened at school as Sophie, which friends asked about me, what homework I’d need to catch up on. I’d coach her through my relationships, telling her exactly what to say to maintain my friendships. We brought whichever one of us was in the basement snacks and contraband books to read during the daylight. Anything to make those hours locked down there alone more bearable.

During my month when I got my first period, I had to teach Scarlet how to use tampons through the basement door for when it would be her period next month. When she broke our arm during her month falling off a bike, I had to wear the cast during mine and pretend I remembered the accident. We kept meticulous journals documenting every interaction, every promise made, every lie told. By the time we were 14 and 15, we’d created an entire fictional person named Sophie, who was really two broken girls desperately trying to exist. We’d lie in the basement together during switches, holding hands, and promising that someday we’d both be real at the same time.

But when I was 15, I developed severe stomach pain during an off month that left me writhing on the basement floor. Scarlet begged our parents to take me to the doctor, but they refused. “Sophie can go when it’s Sophie’s turn,” Mom said coldly. By the time my month came, I could barely stand. But at the doctor’s office, all the tests came back normal. The pain had mysteriously vanished the moment I became real again. Two weeks later, during Scarlet’s month, the agony returned. I lay in the basement vomiting blood while she sat in school, healthy and terrified. We realized my body only let itself be sick when I didn’t exist.

The second I became Sophie again, it suppressed everything to survive my month of visibility. That night, Scarlet and I made a decision. We both walked upstairs to our parents’ bedroom.

“This is calling me,” I told them, showing them my bloody clothes. “We need to stop the switching, please.” For the first time in years, they actually seemed to listen. Mom’s face softened. Dad put down his book. They looked at each other for a long moment.

“You’re right,” Mom finally said. “This has gone on too long. We need to make a permanent decision.”

Relief flooded through me until I saw dad’s expression. “He wasn’t agreeing to let us both exist. He was solving a different problem entirely.”

“We’ll keep one daughter,” he said calmly. “The other one? Well, accidents happen, especially to sick teenage girls who don’t technically exist.”

Mom nodded, touching my face almost tenderly. “We have a week to decide which Sophie we want to keep. You two can make it easier by telling us who deserves to live.”

I stumbled backward, but mom continued in that same gentle voice. “Scarlet is younger, more adaptable, but Sophie has seniority, better grades, but she’s weaker. Do we want to deal with a lifetime of these stomach issues?” She pulled a bottle of pills from her nightstand. “These are painless. Whoever we don’t choose will simply go to sleep.”

Dad smiled at our horror. “You wanted a permanent solution. This is permanent. One daughter like we always planned. The other one never existed at all.”

He looked between us like he was choosing produce at the market. “So help us decide. Who’s the real Sophie? Who gets to live?”

Scarlet grabbed my hand, and I felt her trembling. After 15 years of sharing one life, we had seven days to convince our parents we both deserved to exist. Or one of us would disappear forever. This time not to the basement, to the ground.

That night, neither of us slept. We sat on my bed, our hands clasped so tightly our knuckles turned white. The bottle of pills mom had shown us seemed to hover in the air between us, invisible but suffocating. Seven days. We had seven days to convince two people who’d spent 15 years denying one of us existed, that we both deserve to live.

The next morning arrived too quick. I watched Scarlet dress in my clothes, preparing for another day, pretending to be me at school. Her hands shook as she buttoned my favorite blue shirt. We’d done this routine hundreds of times, but never with death hanging over our heads. Mom made breakfast like nothing had changed. She hummed while scrambling eggs, setting one plate at the table, just one, like always. Scarlet sat down while I stood in the corner, invisible as required during her month.

Dad read his newspaper, occasionally glancing between us with that calculating look I’d seen at the market when he compared prices. After Scarlet left for school, I retreated to the basement. The concrete walls felt colder than usual. I pulled out our shared journal and began writing frantically. Every memory of Scarlet being strong, being smart, being necessary. Every time she’d saved me during her months, every reason they couldn’t take her from me.

Hours later, I heard footsteps on the stairs. Not Scarlet’s light tread, but mom’s deliberate descent. She rarely came to the basement during off months. My stomach clenched, the familiar pain flaring. She sat on the bottom step studying me in the dim light. Her fingers drummed against her knee as she examined my hunched posture. The way I pressed my hand against my stomach, making calculations, weighing options. She left without saying a word.

When Scarlet came home, she found me curled on the basement floor, sweat eating my forehead. The pain had intensified after mom’s visit, as if my body knew it was being evaluated. Scarlet helped me sit up, wiping my face with her sleeve. That evening, we heard our parents talking in the kitchen, their voices carried through the floorboards.

Mom described my condition in clinical detail. Dad responded with questions about Scarlet’s academic performance. They discussed us like items on a spreadsheet comparing assets and liabilities. Scarlet snuck down after they went to bed. She brought soup she’d hidden in her room, feeding me small spoonfuls. We didn’t talk about what we’d overheard. Instead, we planned.

The next day, Scarlet made mistakes at school, deliberate ones. She failed a pop quiz she could have aced. She forgot my best friend’s birthday. She stumbled through a presentation I’d prepared weeks ago. When teachers asked if everything was okay, she just shrugged. Let them think Sophie was falling apart. I spent the day practicing looking healthy. I forced myself to stand straight despite the pain. I did jumping jacks until I collapsed, then did them again. If mom came down, I wanted her to see strength, not weakness. She didn’t come.

That night, Scarlet reported her sabotage. Our parents had already received two concerned emails from teachers. Dad had frowned at dinner, asking why Sophie’s grades were slipping. Mom had noticed Sophie seemed distracted, different. We were both breaking the perfect daughter they’d created. Maybe if neither of us fit their ideal, they’d have to keep us both. Or maybe we were just giving them more reasons to start fresh.

On the third day, I heard dad’s footsteps on the basement stairs. He moved differently than mom, more purposeful, less observant. He carried a clipboard and pen. He asked me questions, not about my health or happiness, but about practical things. How well did I know Scarlet’s routines? Could I replicate her handwriting? Did I know her teacher’s names from when she attended elementary school in a different district before we moved? I lied. Told him I barely knew anything about her life outside our shared Sophie identity. Made myself seem incapable of taking over her existence if they chose to keep her instead.

His pen scratched against paper with each answer. When he left, I vomited blood into the bucket I kept hidden behind the water heater. The stress was accelerating my condition. My body was betraying me at the worst possible time. Scarlet found me that night barely conscious. She cleaned me up, held me while I shook. We revised our plan. She would start showing signs of the same illness. I wonder what’s really going through the parents’ minds when they talk about their daughters like items on a shopping list. The way they’re comparing grades and health problems like they’re picking between two cars makes me curious about what kind of people could think this way about their own children. Make them think it was contagious that keeping either of us meant dealing with a sick child.

The fourth morning, Scarlet clutched her stomach at breakfast. Mom’s eyes sharpened, watching as she pushed away her eggs. When Scarlet ran to the bathroom, I heard wretching sounds. Real or fake, I couldn’t tell. Mom followed her. Through the floorboards, I heard concerned murmurs. Scarlet playing up symptoms. Mom asking pointed questions. The bathroom door closing with finality.

I spent that day writing letters. One to every friend I’d made, every teacher who’d shown kindness. If I disappeared, I wanted some record that I’d existed, that there had been two of us all along. I hid them in the loose brick I discovered years ago. Scarlet came down that night looking pale. She’d made herself sick for real, forcing herself to vomit until her throat was raw. Mom had taken her temperature, examined her closely. The performance had been convincing, too convincing. We heard our parents arguing that night. Mom wanted to make the decision immediately. Why wait if both daughters were defective? Dad insisted on the full week. He had spreadsheets to complete, variables to consider.

On the fifth day, something changed. Our parents stopped discussing us when they thought we couldn’t hear. The house fell silent except for necessary communication. Scarlet went to school. I stayed in the basement. Neither parent visited. The silence was worse than their debates.

That night, Scarlet didn’t come down immediately after our parents went to bed. I waited, pressing my ear against the door. Finally, I heard her footsteps, but they stopped at the top of the stairs. She whispered through the door that mom had installed a lock, a padlock on the outside, keeping me in or her out. We pressed our palms against opposite sides of the door, whispering plans through the crack at the bottom. We had two days left.

The sixth morning, I woke to find a tray of food at the bottom of the stairs. Real food, not the usual scraps. Fresh fruit, warm bread, even juice. A final meal. I realized they’d made their decision. I didn’t eat any of it.

Scarlet must have noticed the lock because I heard her arguing with our parents that evening. Her voice rose higher than I’d ever heard it. Mom’s responses stayed eerily calm. Dad’s silence spoke volumes. I spent that day preparing, not for death, but for what Scarlet and I had whispered through the door, our last desperate plan. Everything depended on tomorrow night.

The seventh day dawned gray and cold. I felt it in my bones, even in the windowless basement. Today, our parents would announce their decision. Today, one of us was supposed to die. I heard Scarlet leave for school as usual. Our parents moved around upstairs, their footsteps creating a rhythm I’d memorized over 15 years. Mom in the kitchen. Dad in his study. The ordinary sounds of a family that had never been ordinary.

At noon, I heard car doors slam. Both of them leaving together. Unusual for a weekday. Were they making final preparations, buying supplies for whatever came next? I tested the basement door. Still locked. But Scarlet and I had prepared for this. I reached under the old water heater where I’d hidden the screwdriver Scarlet had smuggled down months ago. My hands trembled as I worked on the door hinges from the inside. Each screw took forever to remove. My weakened fingers struggling with the rust. The metal scraped and protested. But finally, the last screw came free.

I pushed the door open carefully, hinges groaning. The hallway stretched before me. Forbidden territory during Scarlet’s month. My legs shook as I climbed the stairs. Each step an act of rebellion against 15 years of rules. The house felt different in daylight. I’d only seen it at night during off months, sneaking to the bathroom when desperate. Now sunlight streamed through windows, illuminating dust motes that danced in the air. Everything looked sharper, more real.

I found what I needed in dad’s study. His laptop sat open on the desk, still logged in. My fingers flew across the keyboard, accessing his files. Spreadsheets filled the screen. Not just about us, but about everything. Finances, insurance policies. One file made my blood run cold. Life insurance. Two policies, both in the name Sophie. One purchased 15 years ago, one purchased last week. The beneficiaries were our parents. The payout was substantial.

I photographed everything with the old digital camera Scarlet had hidden in the basement ceiling tiles. Then I searched deeper. Medical records, school documents, everything that proved two daughters existed, not one. Mom’s car pulled into the driveway. I ran, my bare feet slapping against hardwood. I made it to the basement just as the front door opened. I pulled the door closed, holding it in place since the hinges were gone. My heart hammered as I heard mom’s heels click across the floor above. She came straight to the basement.

The door knob turned. I held my breath, pressing my weight against the door. She pushed harder. The door shifted slightly. Then her phone rang. She answered it. Her voice muffled through the door. After a moment, her footsteps retreated. I heard her car start again and drive away. I spent the rest of the afternoon preparing. I wrote everything down, made copies of the photos. I hid evidence in multiple places throughout the basement. If something happened to me, Scarlet would find it.

When Scarlet came home from school, she went straight to her room as instructed. I heard her moving around, following our plan. She was packing but making it look like she wasn’t taking things that wouldn’t be missed, preparing for what came next.

Our parents returned together that evening. They called Scarlet to the living room. I pressed my ear to the basement door, straining to hear. Mom’s voice carried down, explaining they’d made their decision. They would announce it tomorrow on the actual seventh day. Tonight was for last preparations. I heard Scarlet go back upstairs. Then footsteps approached the basement door. Dad’s heavy tread. He tested the lock, rattling it. Satisfied, he walked away. Hours passed. The house settled into sleep. I waited, counting minutes.

At exactly 2:00 a.m., I heard Scarlet’s signal. Three taps on the heating vent that connected her room to the basement. I responded with three taps of my own. Then I got to work. The loose brick came free easily after years of practice, but instead of hiding something, I retrieved what I’d placed there earlier. The bottle of pills from mom’s nightstand. I’d taken them during my escape to dad’s study. I crushed two pills into powder, then carefully returned the bottle to its hiding spot. The powder went into a small envelope I’d made from notebook paper. This was our insurance policy.

The next morning, I heard Scarlet getting ready for school, but then mom’s voice telling her to stay home. Today was too important for school. My stomach dropped. We hadn’t planned for this. I heard them all in the kitchen. Breakfast sounds, normal family noises that weren’t normal at all. Then footsteps approaching the basement. Multiple sets. The door opened. All three of them stood there.

Mom held a tray with breakfast, real breakfast, eggs, bacon, toast. Dad carried two chairs. Scarlet’s face was pale but determined. They set up the chairs in the basement. Mom placed the tray on a box between them. Then she and dad sat down, looking at us expectantly.

Mom explained their decision process, how they’d weighed every factor, how they’d considered our futures, how they’d thought about what was best for everyone. Her voice stayed calm, reasonable, like she was explaining a vacation plan, not a murder. Dad pulled out his clipboard. He read statistics about single children versus siblings, success rates, happiness indexes, cost analyses, all supporting their choice to keep just one.

I watched Scarlet’s face as they talked. She kept her expression neutral, but I saw her hand slip into her pocket. The envelope, she had it. Mom stood up, smoothing her skirt. She announced they’d chosen to keep Scarlet. I was older, sicker, more damaged by years of basement living. Scarlet had more potential, more years ahead. It was the logical choice.

She pulled out the med bottle. My heart raced, but I kept my face blank. She poured a glass of water from a pitcher she brought. Then she held both out to me. I looked at the pills, then at Scarlet. She gave the tiniest nod. I reached for the bottle, but then Scarlet stood up. She snatched the water glass from mom’s hand and drank it all in one gulp. Mom frowned, started to speak. Scarlet grabbed the pitcher and poured another glass. She drank that, too. Mom’s annoyance turned to confusion. She demanded to know what Scarlet was doing.

Scarlet just smiled and poured another glass. This time, she held it out to me. I understood. I took a glass and drank deeply. The water tasted normal. Scarlet poured another. We passed it between us, drinking