The moment carbon monoxide poisoning made me convulse and cough up blood, my mother was on the other side of the door, gently coaxing me to sleep.

My parents were the town's most celebrated philanthropists. They'd adopted Harrison Chavez—the orphaned son of a fellow patient who'd died of a terminal illness. To help heal his trauma, they didn't even dare raise their voices around him.

Then came the day the blizzard sealed the mountain roads, and I—a severe asthmatic—spiked a high fever.

Harrison said he wanted to see what I'd look like smoked black as charcoal. He smashed the oxygen concentrator I depended on to survive, dragged a burning coal stove filled with cheap briquettes into my tiny, windowless bedroom, and locked the door from the outside.

The thick smoke choked me until I was vomiting blood. All I could do was pound on the door and beg for help.

My mother's voice floated through from the other side, soft as a lullaby. "Be good, Libby Chavez. Your brother just wants to keep you warm. He means well. You mustn't lose your temper and hurt his feelings."

My father sighed through the door. "This girl gets more ungrateful the older she gets. Let her stay in there and think about what she's done."

I stopped pounding.

I let the carbon monoxide strip my consciousness away, piece by piece.

In the moment my eyes fell shut, I thought: Tomorrow, at least, I won't have to watch the three of them play happy family without me.

……

In the last second before everything dissolved, I heard Harrison laughing outside the door.

"Big sister's warming herself by the fire in her ice castle! She's about to turn into Cinderella!"

Then everything went quiet.

My body felt weightless, drifting above the spare bedroom that reeked of scorched coal. Smoke no longer seeped through the crack under the door. Inside the sealed room, the fumes had settled, coating the walls in a layer of black grime.

I looked down at the body curled on the floor.

It was me—shriveled into a tight ball from the heat.

The cotton blanket over me had burned through in several places, exposing skin blackened with soot. Shattered pieces of the oxygen concentrator lay scattered everywhere, its plastic casing melted into a hardened puddle.

I tried to move but realized I couldn't feel any pain. That was fine, too.

Voices carried through the wall from outside the door. Every word came through perfectly clear. My mother was on the phone.

"Yes, cancel it. We're not doing the lung rejection surgery tomorrow. Give that private sterile room to Harry instead."

She kept her voice deliberately low against the receiver, her tone dripping with sincerity.

"It's fine. Libby's always been tough—a few more days won't kill her. Harry lost his birth parents. As his adoptive parents, we have to give him the highest level of security and comfort. Don't you think?"

But that surgery was the anti-rejection procedure I'd waited seven months for.

My respiratory system was failing a little more each day. My doctor had said that if we delayed any longer, I might not make it to spring.

She knew. She knew all of it.

Harrison's voice drifted in from the living room.

"Mommy, look! I sealed up all the cracks around the door!"

He ran to my bedroom door holding a can of industrial expanding foam sealant, spraying it along every gap and vent.

White foam expanded and hardened, sealing off the last of the air.

"Trapping the poison gas inside!"

He clapped his hands, bouncing with excitement.

My father walked over and ruffled his hair.

"Harry's so clever—he even knows about soundproofing. Now your sister can throw all the tantrums she wants in there without keeping you up."

Harrison pouted and burrowed into my father's arms.

"Daddy, are you gonna write that article today? The one that says nice things about our family?"

My father smiled.

He opened his laptop and typed a headline into the backend of the neighborhood Facebook page: "Let Love Melt the Snow: One Hundred Days and Nights of Adopting a Terminally Ill Orphan."

The cover photo was that picture-perfect family portrait from the living room. Harrison beamed in my father's arms. My mother stood beside them, gazing at him adoringly.

I wasn't in the photo.

But I was in the article.

"Our eldest daughter, Libby, fully supports our decision to adopt Harry. She says she's thrilled to finally have a little brother, and it makes her happy every single day."

Less than an hour after the post went live, it had over five thousand views.

The comments section exploded.

"Mr. and Mrs. Chavez are absolute saints. Who in this day and age would adopt a terminally ill orphan?"

"Libby sounds like such a good girl. She's so lucky to have been born into your family."

"This is what community spirit looks like! Someone nominate them for the Family of the Year award!"

Dad scrolled through the comments, his grin stretching wider with every one.

Mom walked over with a cup of tea and leaned in to look at the screen.

"Honey, don't reply to too many. It'll look calculated."

Dad grunted in acknowledgment.

"As for Libby, let her cool off one more night."

Mom nodded.

I floated above their heads, watching all of it.

Outside the window, snow fell in thick curtains.

The entire town was cheering for "the most loving parents in the world."

And the carbon monoxide concentration inside their biological daughter's room was enough to kill.

The day after the surgery was canceled, Mom got a sales call from an educational consultancy.

After she hung up, she turned to Dad. "There's a top-tier child trauma therapist. One-on-one sessions, twelve hundred dollars an hour. I think it'd be perfect for Harry."

Dad thought it over.

"Sign him up."

"What about Libby's surgery..."

Mom hesitated.

"We already got the refund on the transplant fees. What's the rush? We'll reschedule after the holidays. Just buy her one of those secondhand harmonicas so she doesn't think we're playing favorites."

Harry came bounding out of his new bedroom—the sun-facing master suite that had originally been mine.

When I was moved into this windowless spare room, Mom's exact words had been:

"Harry has PTSD. He needs plenty of sunlight and open space. You're the big sister. Make the sacrifice."

So I did.

I gave up the room. I gave up the oxygen concentrator. I gave up the asthma inhaler. And finally, I gave up the surgery that was supposed to keep me alive.

Harry tugged at Mom's sleeve, swinging it back and forth.

"Mommy, Mommy, is sissy still in there throwing a tantrum?"

Mom slid a sheet of paper under the door.

I knew exactly what was on it.

Last night, Mom had told me to sign a "Be Grateful to Your Brother" pledge. When I refused, she locked me in.

"Libby, I reprinted a fresh copy of the pledge for you. Whenever you're ready to come out and sign it, just say the word. I'm not forcing you, but think about how pitiful Harry is. His birth parents are gone. Do you really have the heart to make him sad?"

No sound came from behind the door.

She sighed, then turned and cupped Harry's face in her hands.

"She's playing dead again. Throwing her little protest."

Dad was directing two delivery men as they hauled something into the living room.

They pried open the massive crate. Inside was an imported grand piano.

Walnut finish. Ninety-eight thousand dollars.

Harry shrieked and threw himself at the keys, hammering out a storm of ear-splitting noise that filled the entire apartment.

Mom crouched down beside him, her face melting with adoration as she wiped his hands.

"Gently, sweetheart. Don't hurt your fingers."

Dad was off to the side, tearing open another package. He pulled out a box of cough syrup and a rechargeable hand warmer.

The cheapest kind available. Ten bucks with free shipping.

"Put these by her door later."

He set them on the shoe rack without a second glance.

"If she's willing to sign and come out, she can have them."

Harry suddenly stopped playing. He tilted his head and stared at my bedroom door.

"Mommy, sissy's room doesn't even have any air getting in. Won't she get all cooked like a piece of meat?"

Mom peeled an orange segment and popped it into his mouth.

"Don't be silly. Your sister's in there meditating and reflecting on her behavior. Once she's done being sorry, she'll come out on her own."

Harry chewed the orange, mumbling through a full mouth:

"Then how come she hasn't made a single sound?"

"Being stubborn, as usual."

Terence didn't even look up. He was busy hanging a banner on the wall.

The banner was a gift from Maplewood Orphanage, embroidered with four gilded words: Boundless Love.

He stepped back two paces, admired it with satisfaction, then pulled out his phone and snapped a photo.

The living room was a picture of warmth and prosperity: the grand piano, the commendation banner, brand-new space heaters.

Harrison was draped over the piano bench, grinning ear to ear.

On the other side of the wall, in the second bedroom, the air had grown so foul that not even a fly could survive in it.

The curled-up body inside was coated in a layer of black grime. In that sealed, windowless space, her body temperature was dropping, degree by degree.

No one knew. No one wanted to know.

The next morning, my mother was up before dawn for the first time in memory.

Not for me.

Director Cara Finch from Maplewood Orphanage was coming for a home visit. It was the first annual check-in since the adoption.

Mom had been cooking since five a.m. The dining table was buried under a feast fit for a holiday spread.

Braised pork shoulder. Sweet-and-sour sea bass. Mushroom chicken stew. The whole apartment smelled incredible.

On the kitchen counter, shoved into the corner, sat a blackened aluminum lunchbox.

Inside were leftover vegetable scraps and watered-down soup from two nights ago. Already sour.

That was mine.

Director Finch was a heavyset woman in her fifties. The moment she walked through the door and took in the scene, her eyes welled up.

"Mr. Chavez, in twenty years running the orphanage, I've never seen a family treat a child the way you treat Harrison. Not once."

Terence waved her off with practiced humility.

"It's only right. Harrison is our own flesh and blood, as far as we're concerned."

Harrison performed a piano piece he'd learned two days ago. He butchered it completely, but Director Finch led the applause.

Riding the warm atmosphere, Mom stood and walked to my bedroom door.

Her expression carried a hint of tenderness.

"Sweetheart, listen to how lively it is out here. I know you love your brother so much that you gave up your room for him, but you still need to eat. Come say hello to Ms. Finch, okay?"

She raised her voice deliberately so everyone in the living room could hear.

From behind the door, nothing. Not a sound.

Director Finch reached over and patted Mom's shoulder.

"Your older daughter sounds like a good kid too."

"She is. Just headstrong."

Terence sighed on cue from the side.

"Teenage girls get jealous easily. She's been sulking ever since her brother arrived. Nothing we say gets through. Last night she threw a fit and locked herself in her room. She still won't come out."

"Oh, that's nothing. You two are doing more than enough."

After the director left, Mom went back to the table to clear the dishes.

Terence's phone was buzzing nonstop in the residents' group chat.

The neighbor from the floor below had sent a long voice message.

"Mr. Chavez, is something leaking in your apartment? Black water's been dripping from my bathroom ceiling since last night, and the whole place reeks like something's burning. What is going on up there?"

Terence typed back immediately.

"So sorry about that, everyone. My older daughter was in a bad mood and burned some scrap paper in her room to blow off steam. I'm really sorry. I'll take care of it right away."

The chat went quiet for a beat. Then the messages came flooding in.

"Burning paper? Mr. Chavez, you're way too soft on that girl!"

"Is your older daughter mentally ill or something? You adopt a little brother and she loses it like this?"

"You and your wife are saints for putting up with that. In my house, she'd have gotten a beating."

Terence replied to each message with apologies.

"It's our fault as parents. We haven't raised her right. Tomorrow I'll send everyone a gift card as an apology, and I'll treat Mrs. Chen to coffee."

Mom said nothing. She just wrinkled her nose.

The smell was getting worse.

A burnt, acrid stench laced with something else entirely was seeping through the cracks around the door and the gaps in the unsealed pipes, creeping into the living room.