Yet Leda could never bring herself to actually say the words. Eris was already gone, she told herself; what good would it do to tear her family apart now? Each time Ilara looked at her with those dark eyes, so full of love, Leda wavered and fell silent. She didn’t want to be the one to break her mom’s heart.

The child in Leda couldn’t bear the thought of her parents splitting up. Her family might be riddled with secrets and betrayals, but it was still her family. And she would rather keep them together, even if it meant sitting on this secret for the rest of her life.

She had earned this, she thought darkly. This twisting, tormenting guilt was her penance, for what she’d done to Eris.

“I’m fine,” she said tightly, in answer to her dad’s question. What else could she say to him, anyway? Hey, Dad, remember how you were having an affair with my friend, and then she fell off the roof? Guess what? I’m the one who pushed her!

“You and Eris were close, right?” her dad persisted. God, why couldn’t he just go away? And why did everyone keep asking that? Just because she and Eris had some friends in common didn’t mean they were attached at the hip.

“We were friends, but not best friends.” Leda was ready to end this conversation. “Actually, Dad, I have a lot of studying to—”

“Leda,” her dad interrupted, and now he was the one who seemed to be desperate, “There’s something I want to tell you about Eris—”

No, no, no. “Sorry!” Leda stood up abruptly, knocking her chair to the floor, and began frantically throwing items in her massive tote bag. She was wearing floral yoga pants and a black zip-up, but it didn’t matter; she needed to get the hell out of here. She absolutely could not stay and listen to her dad’s fucked-up confession about how he’d been sleeping with her so-called friend. “I’m late to study at Avery’s. Can we talk later?”

Understanding, and a little bit of hurt, flashed in her dad’s eyes. Maybe he knew that she knew. “All right. We’ll talk another time.”

“Thanks! See you later!” she said with false brightness, and ran blindly out of the apartment.

Only after she’d slipped inside a hover did Leda realize she had no idea where she was going. Of course she couldn’t actually head to Avery’s. It was too late for a workout class at Altitude, though she could go to the coffee bar there … but then she might see Avery or, worse, one of Eris’s parents … Leda was far too angry and shaken up for that.

The hover started beeping angrily, indicating that it would charge her for the delay if she didn’t enter a destination soon, but Leda couldn’t be bothered to care. God, what had her dad been thinking, bringing up Eris? Why would he make that kind of confession to his own daughter?

Leda felt like everything was spinning wildly out of control. If she hadn’t sworn never to touch drugs again, she would be searching for a xenperheidren right now; but it had become a matter of pride, and Leda’s pride was matched only by her stubbornness.

She hated thinking about that night. Of course, Leda knew that she was safe: no one could prove what she’d done to Eris. There’d been no cameras on the roof, no way for anyone to find out that it was Leda’s fault. Nothing except her three witnesses.

Come to think of it, maybe she should check in on them, make sure they were sticking to their story.

Suddenly Leda knew exactly where to go. She entered an address in the hover’s system and leaned back, closing her eyes. This would be fun.

WATT

WHAT IF YOU compose the first draft, then I tweak it to sound like me? Watt begged Nadia for at least the tenth time.

“May I remind you that last fall, you gave me firm orders never to write anything for you again. These are instructions from your past self.”

Last fall Watt had been called into the school office for plagiarism, because Nadia’s essay had come out a little too perfect. He’d been more careful since then. These are extenuating circumstances, he thought huffily.

“I’m just the messenger. Take up the fight with your past self.”

“Nadia—”

“That’s it. Per your past instructions, I’m turning off. Wake me up when you have a draft,” Nadia replied, and beeped into silence.

Watt stared at the blank monitor uncertainly. It was true; he had definitely told Nadia to turn herself off if he kept begging her to write his papers. Past Watt was too damned clever for Present Watt to want to deal with right now.

He began speaking aloud, his dictation-screen picking up the words as he said them.

“The reason I want to work with quantum computers is …”

He paused. There were a million things he could discuss in this essay: that quants were faster and smarter than people, even though people had made them, of course; that they could solve problems that humans never dreamed of. God, just a hundred years ago, it took a digital computer several hours to factor a twenty-digit number. Nadia could do it in four seconds flat. Watt couldn’t even imagine what she would be capable of if she were linked to other quants—and put in charge of international trade, or the stock market, or even just the operations of the U.S. food bank. Nothing would go to waste anymore. Human error would be virtually eliminated.

But none of that had to do with Watt on a personal level, or why the program should choose him over the other thousands of applicants.

If only he could write about Nadia, about how unerringly good she was. She can’t be good; she’s a machine, he corrected himself. But Watt knew that at his core, he believed in Nadia’s good intentions as if she had a human conscience.

He thought of what Vivian Marsh had said, that she wanted to personally read his application essay, and felt his heart sink.

“Watzahn!” His mom knocked at his door. “Your friend is here. For your group project.”

“Cynthia?” They had a video to make for English class. He wondered why Cynthia hadn’t warned him that she was coming over. “You should have pinged, we could have met at the library,” he added, opening the door—only to see Leda Cole standing there, wearing pink floral yoga pants and a self-satisfied smirk.

“We could’ve,” she said smoothly, “but I wanted to use your computer. It’s so much better than the ones at the library, you know?”

“Of course. Watzahn is so proud of his computer. He works on it all the time!” Watt’s mom pronounced, beaming.

Quant on, Watt thought frantically, feeling disoriented and blindsided. What the hell was Leda Cole doing here?

“Thank you, Mrs. Bakradi,” Leda said sweetly, her eyes wide and innocent. She stepped into Watt’s room and swung a tote bag onto the floor, kneeling as if to get out the fictional homework assignment. Watt stared in shock at his mother. He couldn’t believe she was even letting a girl into his bedroom. But Shirin just nodded and smiled at Leda, reminding them to let her know if they needed anything. “Don’t work too hard!” she said, and shut the door quietly behind her.

“Sorry I’m not Cynthia,” Leda purred. “Though I’m glad to hear that one of us has moved on from the Fuller siblings.”

“She’s just a friend,” Watt shot back, then felt ashamed that he’d risen to her bait.

“Too bad.” Leda’s fingers kept tapping against the floor. He didn’t think she was on anything—her eyes were too clear, her gaze steady—yet there was a taut, thrumming nervousness to her movements.

He knelt next to Leda and took her bag from her hands. “Seriously, you need to go.”

“Come on, Watt. Be nice,” she admonished. “I came all the way down here to talk to you.”

“What the hell do you want?” he demanded. Watt, be careful, Nadia cautioned. He let his hands fall uselessly to his sides, clenching them into fists, and sat back on his heels.

“I thought you knew everything, with your little supercomputer tracking all of us all the time,” Leda said acerbically.

Nadia, if you hadn’t turned yourself off, I wouldn’t have been caught like this!

Perhaps you shouldn’t have violated the guidelines you set for yourself, Nadia replied, with ruthless logic.