“I loved you enough to give you up,” he says. “When I used the Firebird for the first time, I knew I might not make it back. It didn’t matter to me; nothing mattered to me as long as you were safe. You could lead your life without me. If I have to give you up again, I will. It feels like—like cutting off your own arm—” His voice chokes off as he glances down at my exposed arm and the dark scar there.

Only then do I realize—Paul may not consciously remember the other versions of himself or the universes they inhabit. His subconscious, however, has been profoundly affected. He can’t see it yet, but I can. This fatalism—Paul’s belief that he could only hurt me—has been built like a wall between us, stone by stone.

Father Paul in medieval Italy thought both God and the church would part us forever. Meanwhile, Lieutenant Markov of the Warverse had already pursued me in vain; he’d resigned himself to watching me love another. The Paul who wound up in the Russian mob? He’s bitter at twenty, surrounded by violence, nearly as much a prisoner as I was, tied up in that cellar. He only knew me as a victim—his victim. And now Paul dwells within the body of a version who lost everything that mattered to him: first the Firebird project, then his close relationship with my parents, then me.

Did Conley do this on purpose? Or was it merely terrible luck? Either way, all the disappointment, anger, and misery of those four lifetimes has taken root within my Paul. He no longer believes in our destiny or in himself.

The past several days have taught me so much about the impact my actions have on the dimensions—and Marguerites—I visit. Now, in Paul’s sorrowful eyes, I see that they have an impact on us too. Maybe I’ve been protected as a “perfect traveler,” but Paul hasn’t. His splintering has exacted a terrible price.

I’ve spent this entire journey trying to bring Paul back from these other universes. But as he stands here in front of me in this Cambridge flat, he feels farther from me than he has ever been.

Talking Paul down from this bleak place will take time—not minutes, not hours, but days or weeks—and that’s time I don’t want to spend in this dimension. When we’re home, he’ll come back to himself. He has to. “Let’s go home, okay? Let’s just focus on Triad and go over this together. We only have so much time to work against Conley. That’s what matters most.”

Paul nods. Having a concrete goal helps him steady himself. “Yeah. Let’s. But—you should head home first. If the other Paul and Marguerite woke up with you in his apartment—”

“That would be bad. All right.” I can’t yet bring myself to step away, though. “You will follow me. You promise.”

“Yes. I promise.”

Then he pulls me close for a kiss.

When our lips meet, Paul clutches me to him—like he never wants to let go. I open my mouth for him, lean into him. The night we planned to spend together, during my parents’ trip: I want Paul to understand that we’ll still have that, and so much else besides. When this is over, we’ll still have each other.

I can tell he’s kissing me this desperately because he thinks it might be the last time. The way I’m kissing him should tell him it’s not. Not even close.

Ten thousand skies, and a million worlds, and it still wouldn’t be enough for me to share with you. Nothing less than forever will do.

By the time we pull apart, I’m shaky. Paul looks heartsick. He puts one hand over the Firebird on his chest. “I’ll see you soon.”

“Okay,” I say as I head for the door.

I refuse to say goodbye.

As I cycle back toward my family’s Cambridge home, I concentrate on the thoughts I need this Marguerite to remember best. She’ll be my messenger to this world, the world we need on our side most of all. We need to know how to communicate throughout the multiverse. That’s the only way we’ll ever be able to defeat Triad. And since Conley spied on this dimension once, he could come back eventually. If he does, and he sees you have this technology, you’ll be in even more trouble than we are. But don’t be scared. I swear, if we work together, we have a chance to win. To be safe from Triad forever.

I know she’ll believe me; she won’t be able to help sensing that I’m telling her the truth. But what will these versions of Mom and Dad do? Will they stand with us, or tell us to stay the hell out?

As my bicycle glides into the driveway of our home, I bring it to a gentle stop. I already scraped one of her knees leaping into her dimension at the wrong moment; the least I can do is avoid scraping the other. I settle the kickstand, brace myself, and prepare to leap.

On impulse, I reach into my bag and pull out a compact. When I flip it open, I peer into the mirror—as close as I can ever come to looking this Marguerite in the face—and I say just one word, “Please.”

After that, I snap the compact shut, drop it into my bag. Across town, even now, Paul is preparing to leap through the dimensions with me. It won’t be our last journey together. I have to believe that.

I take the Firebird in hand and watch this world vanish, like watercolors rinsing away.

Returning to my own body is always so much easier than any of the other jumps. Everywhere else the collision of selves jolts me in a way my parents haven’t been able to scientifically explain. But coming home? That’s as easy and effortless as slipping into a warm bath.

I open my eyes to see Theo standing above me. Though his face is too pale, his eyes shadowed, he smiles as he says, “About time you got here.”

“Good, you made it. How do you feel?”

He makes a face as he scratches the back of his head. “I’ve been better. But, hey, you got the juice, right? The data for the juice, I mean.”

“Right. You’ll be feeling better in no time.” I rise from my bed and walk into the main area of the house in search of my parents. Theo must be as ready as I am to put them to work re-creating this solution. “Where are Mom and Dad?”

“They were out when I got here. Probably at the university labs, trying to figure some other way out of this, or building another Firebird.”

No doubt. Well, they’ll be back by dinnertime, because they never eat on campus if they can help it. From the slant of the sunshine through the glass door to our deck, I can tell it’s midafternoon. “Have you checked to see if Paul has come back yet?”

“You found him, huh?” Theo doesn’t high-five me, or celebrate in any obvious way. This is kind of odd—I’ve seen him do a victory dance just because he managed to flick a paper clip into his hat from across the room—but then I remember how weak he is. He’s back in this battered body, the one on the verge of failure. We don’t have any time to lose.

A wave of powerful vertigo sweeps over me, making my stomach flip-flop as the whole world goes sparkly and dark. “Whoa,” I say, putting one hand to the side of my head. “What was that?”

Theo puts one hand on my shoulder, only a touch. “You’ve been through a lot. No wonder you’re tired.”

Tired is not what I just felt. The Firebird has to have operated correctly; if it hadn’t, I wouldn’t be home now. Whatever this sensation is, it hasn’t left me. At least it’s not so strong that I can’t shake it off.