Chapter 4: The calculus of us

Thursday nights were usually reserved for the math club’s peer-tutoring sessions, but the library was closed for renovations. That left me sitting on the floor of Noah’s bedroom, textbooks spread out like a minefield between us.

Madison was at a "Captains Only" dinner across town, which meant the house was uncharacteristically quiet. Michael was at the station, and Elena had retreated to the den with a book, leaving us in a bubble of yellow lamplight and the faint hum of the central air.

"I don't get it," Noah muttered, shoving his fingers through his dark hair until it stood up in messy peaks. "If the limit approaches infinity, why does the slope stay constant? It feels like a lie."

"It’s not a lie, Noah. It’s just logic." I reached over, pulling his notebook toward me. My fingers brushed his, and for a split second, neither of us moved. The air in the room felt suddenly charged, like the static before a lightning strike.

I cleared my throat, focusing intensely on his messy handwriting. "Look at the graph. As x increases, the change in y becomes negligible. It’s about perspective."

"Perspective," he repeated, his voice dropping an octave. He wasn't looking at the notebook. He was looking at me. "Is that what you’re doing? Changing your perspective so you can leave?"

I dropped the pen. "Noah, we talked about this. Chicago isn't about leaving you. It’s about me finding out who I am when I'm not 'the girl the Callahans took in.'"

Noah shifted, sitting up straighter. The bedframe creaked. "You’ve never been that to me, Isla. Not for one second. You were just... you. The girl who knew all the constellations. The girl who cried when we found that bird with the broken wing in fifth grade."

"I was a kid then," I whispered.

"You’re still that girl," he said, his blue eyes intense. "Just with higher walls."

He reached out, his hand hovering near my face before he settled for tucking a loose curl behind my ear. His touch was warm, lingering just a second too long to be accidental. My heart hammered against my ribs..a scared, trapped bird.

"I found something today," he said, breaking the silence. He leaned over and pulled a crumpled piece of paper from his bedside drawer.

It was a drawing. Crayon-smudged and faded. It showed two stick figures standing in front of a lopsided house with a giant sun in the corner. In a child's shaky handwriting, it said: Noah and Isla’s home .

"You kept this?" I asked, a lump forming in my throat. I remembered drawing it a week after I moved in. I had been so afraid they would send me to the foster agency if I wasn't "grateful" enough.

"I keep everything, Isla," he said softly. "Because I’m terrified that one day I’ll wake up and you’ll have decided that I’m just part of a past you want to forget."

"I could never forget you, Noah."

The honesty hung between us, thick and heavy. He leaned in, his face inches from mine. I could see the golden flecks in his blue eyes, the slight scar on his chin from a fall off his bike when he was twelve. The world narrowed down to the space between our breaths.

Then, his phone vibrated on the nightstand.

The screen lit up with a photo of Madison laughing, her arm around Noah’s neck. The caller ID read: Mads ❤️.

The spell shattered. I pulled back sharply, the cold air rushing in to fill the gap he’d left.

"You should answer that," I said, my voice trembling.

Noah didn't look at the phone. He looked towards me, his expression a mix of frustration and raw longing. "Isla.."

"No, Noah. You have a girlfriend. I have a bus ticket to a future that doesn't involve breaking this family apart. Let’s just... let’s just finish the derivatives."

He stared at me for a long beat, the phone continuing to buzz like a warning siren. Finally, he reached out, grabbed the phone, and silenced it without looking. He didn't answer her, but he didn't lean back toward me either.

We spent the next hour in a silence that was anything but quiet. Every time our hands moved near each other, we flinched. Every time our eyes met, we looked away.

By the time I gathered my books to leave, my chest felt like it had been hollowed out. I paused at the door, my hand on the frame.

"Noah?"

He was sitting on the edge of his bed, his head in his hands. "Yeah?"

"Why did you stop Madison from going to West State? You told her you were looking at other schools."

He looked up and said” I don’t think it would be fair to promise her something I’m not sure I can give”, his gaze steady and devastating.“ I didn't stay to hear the rest. I ran to my room and shut the door, leaning against it as the first sob finally broke through. I was eighteen years old, and I was realizing that the hardest thing about having a home isn't finding it,it’s realizing you’ve fallen in love with the foundation.

And foundations aren't meant to be moved.