The tiny red digital numbers on the microwave read 2:14 in the morning when the house finally went quiet enough for my ears to stop ringing. I was sitting on the edge of the worn floral sofa in the living room with my cold anthropology textbook propped open on my knees, though I hadn’t read a single word on the page for an hour.

Down the hall, Mom let out that familiar, rattling sigh through her oxygen mask, a sound that meant her lungs were tightening up again and she would need her inhaler before dawn.

I set the textbook face-down on the cushion and rubbed my eyes until I saw flashes of yellow light behind my eyelids. My lower back felt like someone had taken a baseball bat to it during my four-hour shift lifting fifty-pound feed bags at the grain elevator, and my summer midterm was coming up on Thursday. But none of that mattered because thirty minutes earlier, my older sister Chloe had grabbed her car keys off the kitchen counter, sprayed a cloud of sweet vanilla perfume that made my throat itch, and walked out the front door to meet her new boyfriend downtown.

Before the baby came a month ago, our house was already hanging by a thread. Mom’s emphysema had gotten so bad she hadn’t left her bedroom since February, and between her copays and the electric bill, my part-time paycheck barely covered my share of the groceries.

Then Chloe got pregnant, the deadbeat dad took off to Kansas City, and my sister moved back into our spare room like she was checking into an all-inclusive resort.

At first, I told myself we had to stick together because we were family. That was the word Chloe threw around like a shield whenever I asked her to wash a dish or check on Mom while I was at my morning classes. But family started looking a lot like unpaid labor around week two, when Chloe realized she could sleep until noon while I heated up the bottles and changed the diapers between my online quizzes.

The breaking point didn’t happen overnight, but it had a distinct sound. It sounded like the sharp, dismissive click of Chloe’s heels hitting our linoleum floor right before she abandoned her newborn daughter for the third time that week. She had already collected her state child support check that morning, spent half of it on eyelash extensions, and left me with twenty bucks for diapers and a sink full of crusty formula bottles.

When I tried to block her path near the entryway that evening and asked her if she had looked into local childcare or even a part-time sitter, she just laughed. It wasn’t a warm laugh. It was that short, mocking snort she had used since we were kids, like I was the dumbest person in the room for even speaking.

“That costs money and you’re family,” Chloe had said, tossing her blonde hair over her shoulder and stepping right past me into the damp night air. “Just don’t let the baby cry too long, okay? I’ll be back late.”

And then she was gone, leaving me standing in the hallway with a one-month-old infant screaming her lungs out because she missed a feeding window.

The next three hours were a blur of cold formula, burp cloths, and frantic pacing while trying to keep my voice down so I wouldn’t wake Mom.

My chest felt tight, the way it always did right before one of my panic attacks rolled in, and my hands shook so badly I dropped the plastic measuring scoop on the floor twice. I sat there in the dark living room rocking my niece back and forth, staring at the pile of unpaid utility notices sitting next to the toaster.

I didn’t cry. By two in the morning, I was past crying. The exhaustion had burned clean through my nerves and left behind something cold and very steady.

The front door finally clicked open around 3:45 AM. Chloe stumbled into the hallway, kicking off her heels and humming softly to herself like she had just spent the evening at a spa instead of leaving a teenager to nurse an ailing mother and a newborn baby. She flipped the kitchen light switch, blinking against the brightness, and padded toward the fridge to look for leftovers.

“You still awake?” Chloe called out, her voice slurred around the edges from whatever drinks she had downtown. “Hope the little one slept for you. She gets fussy around midnight, I’ve noticed.”

I didn’t answer from the living room shadows. I just stood up, picked up the neat stack of bills and the spiral notebook where I had spent the last two hours doing some very careful math, and walked into the kitchen.

Chloe was leaning against the counter with a carton of orange juice in her hand, her mascara slightly smudged under one eye. She stopped with the carton halfway to her mouth when she saw my face.

“What?” she asked, dropping her voice into that defensive whine she used whenever she knew she was caught. “Why are you looking at me like that? I needed a break. Being a mom is hard, you know.”

“You have twelve hundred dollars in child support sitting in your checking account from the first of the month,” I said. My voice didn’t shake once. It sounded flat and distant, like someone else was talking.

Chloe put the juice down with a sharp thud that splashed a few drops across the white laminate. “What does that have to do with anything? That’s for her clothes and stuff.”

“It’s for her care,” I said, laying the notebook right on top of the orange juice carton. “Electricity is three hundred and twelve dollars. Mom’s oxygen refill is two hundred. And I spent forty-five dollars of my own grocery money on formula today because you spent your check on your eyelashes.”

Chloe crossed her arms, her jaw tightening up. “Don’t start with this. We agreed to share the load. That’s what sisters do.”

“No,” I told her, stepping closer so she couldn’t look away. “You agreed to have a baby and then outsource your entire life to me while you go out with guys who don’t even know you live with your mother. That’s not sharing. That’s using me.”

“I live here too!” she snapped, her voice rising enough that a faint cough echoed from Mom’s bedroom down the hall. “You think it’s easy for me? I’m exhausted!”

“You’re going to be a lot more exhausted starting tomorrow,” I said, and for the first time all night, I let myself smile just a little bit. “Because I’m not changing another diaper until you buy the supplies with your own money. And if you go out tomorrow night without a paid babysitter lined up, I’m packing a bag for both of you and calling Aunt Denise.”

Chloe stared at me like I had just spoken a foreign language. Her mouth opened, closed, and then opened again. “You wouldn’t do that. You’re family.”

“That word doesn’t mean what you think it means anymore,” I told her, turning my back on her and walking toward the hallway. “The baby has a nine o’clock feeding. You’re on duty.”

I didn’t wait to see what she said next. I walked back to my small bedroom, closed the door behind me, and lay down on top of the blankets with my clothes still on. My phone buzzed once on the nightstand with a reminder about my anthropology midterm, but I ignored it, closing my eyes against the dark.

The house stayed quiet for a long time after that, save for the hum of Mom’s oxygen machine and the faint, angry sound of Chloe shuffling around the kitchen cabinets next door.