I think of the ocean that hugs the city of Santa Cruz, and it makes me miss the Mississippi River in Minnesota.

“Selene’s super powerful.”

“Is she?” I ask. “I mean, the moon might be powerful, but what about her? She doesn’t do anything as the moon. No purpose. Her brother Helios is way more powerful. What about Hera?” I try. “She’s a girl.”

“Ugh!” Mercedes groans. “Hera’s always trying to get revenge.”

Mercedes and I stare at each other.

“We’re doing Selene.” Her voice is cold and hard.

There are those eyes again.

“Besides,” she adds breezily, “I don’t think it matters. We’re getting graded on our projects and my idea for a night sky diorama will be an A-plus project for sure.”

I blink. Her brown eyes are so familiar, like looking in a mirror. “Fine,” I say at last. There really is something about Mercedes that makes you agree with her. Even if you don’t want to.

“That’s settled,” she says, and pulls a beat-up three-ring binder from her backpack. I open my folder, which is still shiny and new in a very uncool way.

“We’ll do this section first,” Mercedes commands. Out the window of Mrs. Ellingham’s classroom, fog creeps in. My mom loves the fog—she loves everything about California. Personally, I don’t like the way the fog hides everything familiar, like it’s keeping secrets from you.

“Matilde,” Mercedes barks. No one ever calls me that. I regret spelling out my full name for her. “Concentrate.” She points to the clock above the whiteboard. “My ride is coming in thirty minutes.”

My mom is picking me up soon, too, so I get to work.

When Mrs. Ellingham returns with a stack of photocopies under her arm, Mercedes and I are silent, bent over our packets. “Well!” Mrs. Ellingham says. “Look at you two.”

I jerk in surprise and so does Mercedes. My doppelgänger is sitting in the exact same position as I am. Left leg tucked, right elbow on the table. We both stop jiggling our right feet at the same time.

“You two could be sisters,” Mrs. Ellingham says brightly.

I’m about to say something to the teacher about doppelgängers. But then I see Mercedes’s face flush red. Not just her cheeks but her neck, too. As red as our old dishes. She stands up so quickly, she knocks her pencils, binder, and Greek myths packet to the floor.

“Sorry to startle you,” Mrs. Ellingham says with a short laugh. “I’ll let you get back to work.” She settles at her desk at the back of the room, hidden behind a stack of books, a pile of papers, and a large file organizer.