The teacher is interrupted by a boy whose hair sticks up in a spike at the back of his head. “Mrs. Ellingham,” he calls out, “why does the new girl look just like Mercedes Miller?”

There are more murmurs. Mrs. Ellingham looks at me. She looks at the girl seated across from my desk. “Mercedes and Mattie do look very similar,” she agrees.

The girl who must be Mercedes Miller is studying her mint-green fingernails like they’re the most interesting thing in the world.

Mrs. Ellingham looks at us like we’re a puzzle. She nods her head of gray hair. She’s tall and looks even taller in the long, billowy dress she’s wearing. “Maybe they’re related,” she suggests.

Related? I’ve never seen this girl before in my life. But there’s a strange twitch in the back of my brain, even as I think this. And, although warm California sun is streaming through the classroom windows, a shiver thrums from my toes to my fingertips. I can’t tell if it’s one of my panic attacks or something else.

Mrs. Ellingham’s bright-pink lipstick creases as she smiles. “Are you two related?”

“No,” we say. Even though we speak in unison, our voices are different. Mine is small and just a little squeaky. Hers is bold, forceful, as if the idea of being related to me is the worst thing in the world.

“Well,” says Mrs. Ellingham, looking from me to Mercedes. “I’m sure you two will end up being great friends.” She smiles again.

She’s the only one smiling.

“In the meantime, let’s get to today’s lesson.”

I scurry back to my seat and resume my spot across from Mercedes. She seems to be pretending that I don’t exist, which is a lot like what everyone has been doing around me lately. My new stepbrothers act like I’m a piece of the furniture, Bob follows my mom around like a lovesick puppy, and my mom juggles the three of them while unpacking and reorganizing our stuff at the new house.

“We’re starting our mythology project today,” Mrs. Ellingham says. She writes the word “mythology” on the whiteboard in swirling letters. “The mythology of a culture reveals that culture’s history and beliefs.” She underlines “mythology” with a flourish. Below it, she writes: “Greek,” “Roman,” “Maya,” “Inca,” “Egyptian.” “Studying the stories of ancient civilizations helps us understand our own lives.”

I think about my new life here in California. I’m pretty sure ancient civilizations aren’t going to help me understand any of this.

“Hey!” I hear a hoarse whisper behind me as Mrs. Ellingham continues to talk about myths. “Hey, Mercedes and new girl.”

I turn around to see the boy with the spiky hair leaning back in his chair. He whispers, “You guys are probably doppelgängers.”

“Doppel-what?” I whisper back.

Mercedes glares at me and the boy.