“Thank you, Lieutenant Markov,” I say. I try to make it sound formal, as though I’m completely unmoved. I fail.

Paul bows his head and goes back to standing at attention like nothing had ever happened. He’s better at pretending than I am.

Christmas Day comes. I spend it in church. That alone would be weird enough for me, the daughter of two people who described themselves as “Confuciagnostics.” And here, “church” means a Russian Orthodox cathedral, with priests who wear high, embroidered hats and long beards, and choirs singing hymns in minor keys, and the smell of incense so thick in the air that I keep hiding my face behind my hand to cough.

As I kneel in my pew, I think of Mom and Josie back home—spending their first Christmas without Dad, and without me, too. By now they know what Theo and I set out to do, but they must also have given up much hope of us ever returning home.

Does she think we’re dead?

I should be with her. Instead I went chasing after Paul because I was too angry to think straight, too upset to slow down and wait until Theo and I were sure of what we were doing. Easy though it would be to blame Theo—he loved Dad nearly as much as I did. He wasn’t thinking any more clearly than I was.

No, it’s my own fault that I’m not with my mother and sister on what must be the worst Christmas of their lives. My fault that Mom’s probably mourning both me and Dad. Shame chokes me, like the smoke from the incense, and the dark sorrowful eyes of the religious icons seem to condemn me from their gilded frames.

That afternoon, we exchange gifts in the tsar’s study. (Thankfully, the Grand Duchess Marguerite is more organized than I am; her gifts were already wrapped and labeled before I got here.) To my surprise, the presents are very ordinary things—Vladimir gave me a fountain pen, I gave Katya lace handkerchiefs, and Tsar Alexander seems perfectly content with a new set of boots from Peter. I would’ve thought royal families gave one another staggering, epic gifts, like emeralds the size of baseballs. But maybe if you’re surrounded by opulence every day, the riches lose their power.

Grand Duke Sergei isn’t included in the family Christmas. No shocker there.

Afterward, Paul accompanies me back to my room, like always, but at the door he clears his throat. “My lady?”

“Yes?”

“If you would do me the honor—if it would not be improper for you to accept—I have a gift for you.”

He looks so unsure, as awkward as my own universe’s Paul ever did. I can’t help smiling. “I have one for you, too.”

A smile lights up his face. “If I may—”

I nod, excusing him, and he hurries to a nearby room, where he must have stashed it. So I get the final wrapped present I found—in red cloth, not paper, with real white ribbon—and hold it in my hands as I wait. What did she buy him?

Paul returns with a small box, also tied up with ribbon. “For you, my lady.”

“And for you.” We hand them off to each other at the same moment; it’s slightly clumsy, and we both laugh a little. I’m vividly aware that we’re doing this at the doorway to my bedroom, where anyone could walk by and see. But the only other option is for me to invite Paul inside, which is about nine hundred kinds of inappropriate. “Here, you go first.”

“Very well, my lady.” Paul deftly tugs the ribbon and cloth away to reveal a book. His eyes light up—he’s thrilled—and I quickly look at the title: The Laws of Optics, Or, The Refraction of Light.

Of course. This Paul and my Paul are enough alike that they’d both be fascinated by science, and this dimension’s Marguerite must have picked up on that. Standing around all day watching me write letters? That’s not enough to occupy Paul’s brilliant mind. Now he runs his hand reverently over the leather binding of the book, like I’ve given him the deepest secrets of the universe.

“Thank you,” he says, obviously struggling for the right words. “I was saving my money for this, but now—I will begin reading tonight.”

This is a world where books are expensive, and the only sources of information. No wonder he’s thrilled. I glow with happiness I don’t deserve; I’m not the one who picked it out, after all.

Already Paul is apologizing. “My gift can’t compare.”

“Don’t be silly.” I unwrap his present as quickly I can, ribbon fluttering to the floor by my feet. As I pull back the lid of the black box, I see a rainbow of colors, and my face lights up. “Pastels! You bought me pastel chalks.”

“I know it is your practice to sketch, my lady. But I had thought—perhaps you might wish to experiment.”

Even in my dimension, I always meant to work with pastels someday. I run one fingertip along the pink chalk, tinting my skin rosy. “They’re beautiful.”

“Not so fine as the gift you gave me—”

“Stop that. Don’t you realize we gave each other the same thing?”

Paul tilts his head. “My lady?”

“Every form of art is another way of seeing the world. Another perspective, another window. And science—that’s the most spectacular window of all. You can see the entire universe from there.” So my parents always said, and as corny as it might be, I believe them. I smile up at Paul. “So it’s like we gave each other the whole world, tied up in ribbon.”

“You want me to learn the entire universe?” His grin is natural, somewhat abashed; we are no longer guard and grand duchess, just a guy and a girl, standing very close. “For you I will.”