“Of course she’s difficult,” Aldo said, still stuck on the initial verbiage. “She’s more than difficult, actually. She’s—” He paused, struggling to explain. “Well, within any equation, there’s variables,” he attempted, and Madeline, like many people he spoke with, gave him a look of amusement mixed with confusion. “You would know this, obviously,” he recalled. “You’re a scientist.”

“Of sorts,” Madeline permitted, and he nodded.

“Most people are relatively simple. A combination of environmental factors, genetic proclivities, inherent traits…”

He checked that she was with him. “I follow,” she said, nodding as if she did.

“Right,” he said. “So most people are fairly straightforward functions of x and y, behaving within constraints of expectation.”

“Social constructs?” Madeline guessed.

“Presumably,” Aldo confirmed. “So within those parameters, some people are exponential functions, but still largely predictable. Regan”—Charlotte,he reminded himself too late, but dismissed it as a foregone error—“isn’t just difficult, she’s convoluted. She’s contradictory—honest even when she lies,” he offered as an example, “and rarely the same version twice. She’s confounding, really intricate. Infinite.” That was the word, he thought, clinging to it once he found it. “She’d have to be measured infinitely in order to be calculated, which no one could ever do.”

He glanced at Madeline, who was giving him a bemused half-smile.

“Does that make sense?”

“Yes,” Madeline said slowly, “it does.”

Aldo decided he liked Madeline.

“Anyway,” he said, figuring he’d gone on long enough. People typically didn’t care for his theorizing, and though there was more he could say on the subject, he forced himself to summarize neatly with, “You shouldn’t apologize for her.”

“No,” Madeline agreed, “I suppose I shouldn’t.”

They were quiet for a moment, as it felt like her turn to speak. She seemed more interested in her own thoughts, though, and when she folded her arms over her chest, Aldo caught the evidence of raised gooseflesh on her arms. His phone buzzed in his pocket; probably his dad asking if he was behaving himself.Try not to stare at the ceiling when other people talk, Masso usually said, which Aldo found difficult. At the moment, his ceiling was a sky full of stars. If he’d had a joint and silence, it would be an evening like any other spent atop his roof.

Except that it wasn’t, he remembered, because Regan was somewhere nearby.

“You’re cold,” he noted to Madeline, observing the way she’d curled around herself for warmth. “You should go back in. I’ll be out here,” he said, and then lied, “I’ll get a drink.”

She nodded, still thoughtful.

“It was nice to meet you,” she said.

“You, too,” he replied with a perfunctory lilt of his head, and then she smiled at him, heading back into the house.

Aldo rolled an invisible joint between his fingers, making his way to the edge of the lawn. When he’d arrived with Regan that morning, he’d noticed that her house overlooked a narrow creek, which he now wished he could see. Instead he could merely hear it, left to guess whether or not it was actually there or simply part of his imagination. Part of him considered leaping in, finding out by doing. Not every problem was best left to theory to explain.

“Brought you something,” he heard behind him, jolting him from his thoughts, and he turned to find Regan approaching from the lawn, sidling up to him. The wind had whipped her hair around her shoulders and she smoothed it away from her eyes, offering him a glance of apology.

“Here,” she said, holding out what remained of a blunt, and he looked down at it, skeptical. “Oh, come on,” she said, rolling her eyes, “I can’t help whatever shitty weed college me left in my old bedroom. It’s still better than nothing,” she reminded him, temptingly wiggling it between her fingers.

He reached out, taking it from her. The pads of her fingers were warm.

“Aren’t you cold?” he asked her neutrally. She shrugged, holding up a plastic lighter and beckoning for him to place the blunt between his lips.

“Not especially,” she said as he complied. She took his chin in one hand, flipping the lighter and holding it up to the end of the blunt, saturating the stunted tip in flames until it smoldered. “There,” she said, obviously pleased with herself as he inhaled. “Better?”

She released his jaw, and he exhaled. It wasn’t especially good weed, but he’d certainly had worse.

“Sure,” he said, eyeing it. “Though it wasn’t too terrible before.”

She seemed to disagree, but dismissed her own feelings on the matter.

“I heard you talked to Madeline,” she said, something of a challenge.

He shrugged. “A bit. Mostly about math.”