When Maire saved Bay’s voice for me in that first shell, it must have been without Bay knowing. That explains why Bay was singing, not giving me a message. The secret of saved voices in shells was between Maire and Oceana, and then between Maire and me. She shared it first with her sister, and then with a siren.

Maire couldn’t have known that Ciro would find the shells. She just hoped that someone would.

“The people here have heard our stories,” Bay says. “They feel like they know us.”

“But they still don’t believe the sirens are human,” True says. “They killed them.”

“Some still hate the sirens,” Bay says. “But there are many, like Ciro, who believe the sirens are human, too, and that getting rid of them is wrong.”

“That’s better than some of the people Below,” I say. “Not many of them think that sirens are human.”

“Rio,” Bay says, and then she stops. What can she say? I’ve had to spend my life hiding my voice, and she’s had to spend her life protecting me, and that’s not what either of us would have chosen. We’ve both suffered because of what I am.

No. Not because of what I am. Because of the way people fear those who are different, when really we are so much the same.

“There’s something I still don’t understand,” I say. “If siren voices are so powerful up here, how did the people Above resist the sirens on the island?”

“I don’t know,” Bay says.

I wish Bay and I didn’t have to talk about all of this. I wish we didn’t have to think of sirens and saving. I could tell her that True kissed me and that I was fast, so fast in the lanes. She could tell me how she feels about Fen and what she dreams of becoming without a siren sister to protect. But there’s no time for that.

Will there ever be time for it again?

I sit down on the floor, suddenly weary. I put my head in my hands. It’s getting harder to breathe, and I can’t stop thinking of Maire.

I feel my sister’s hand on my back.

“There are people who will help us,” Bay says. “I’ve met many of them. They come to minister to those of us from Below who work in the labor camps.”

“What do you mean about working in the labor camps?” I ask. Fen coughs in the background, and he sounds horrible. “Fen doesn’t sound like he should be in a labor camp,” I say. “He sounds sick.”

That makes Fen laugh. “They don’t care about that,” he says. “They’re not concerned about our health.”

“They only let us keep coming up from the Below because we’re free labor,” Bay says.

“They think we’re stupid,” Fen says. “And they’re right. We don’t know the first thing about the way the world really is.”

“They work us to death,” Bay says. “We’re allowed a free hour or two at night, and that’s when we’re supposed to come into town and take care of whatever needs we might have. We make a single coin a day. It’s enough to buy only the smallest amount of food at the worst shops.”

“You know your sister,” Fen says, grinning at me. “Instead of getting anything to eat that first day, she headed straight for the temple.”

“It was good we did,” Bay says, “because we met Ciro. Now we come here every night.”

No wonder she looks exhausted, if she works all day and then comes to the temple in the evening.

“I’m sure that the gods would forgive you if you missed a few prayers,” I say.

Fen laughs again. “We don’t just come for the gods,” he says. “We come to show the people of the Above that we’re like anyone else.”

Fen starts coughing again, harder this time. It sounds terrible, dry and achy and bone-breaking. The air up here is still not clean, but he seems to be affected more than anyone else.

I glance over at Bay, at her tired eyes and her short hair, and I wonder if she cut it off because she couldn’t braid it without me, or if she cut it off so she wouldn’t have to remember me, or for a reason that had absolutely nothing to do with me.

“Please,” she says to Fen. “Put it on.”

I realize that she means the mask, which he holds at his side.

“I feel like I can’t breathe at all when I’m wearing that thing.”

“But it does help,” she says. “Even if you can’t tell. It buys you time.”

“We’re not sure of that,” Fen says. But he puts on the mask.

“The air Above,” I say, “is it doing this?”

“No,” Fen says, his voice sounding like mine now, flat and neutralized through the mask. “I have water-lung. I had it before I came Above. The air isn’t helping, but I’d be in trouble anyway. The mask helps me breathe.”

My heart sinks for my sister. There’s no cure for water-lung.

“How long have you known?” True asks, looking as stunned as I feel.

“I figured it out a few months before the celebration of the Divide,” Fen says. “I could feel it happening.”

“You didn’t tell me,” True says.

“I didn’t tell anyone. They sell stuff in the deepmarket that can help you keep from coughing so that no one will know. It’s not good for you, but I didn’t care. If I was going to die anyway, what did it matter? That’s when I started swimming in the night races, to keep my mind off things. And that’s where I met Bay. When I found out she was going Above, I decided to come with her.”

“We’ve learned since that there are doctors here who might be able to help Fen—they’ve gotten good at fixing people’s lungs with all these years of pollution—but no one will waste any time on someone from the Below,” Bay says.

“It’s all right,” Fen says. “We didn’t know that when we came. I just hoped to be with you and see the Above before I died.” He smiles at her and she smiles back immediately, lights up as hot and bright as the sun in an instant. She loves him.

And he’s in love with her. I can tell from the things he says and from the way he looks at her.

She told him she was leaving.

But she didn’t tell me.

Because she thought she had to protect me.

For a minute anger breaks over me as strong as waves against rocks. Anger at my mother and my sister, for loving me but always sheltering me. Anger at the people Below who want to contain the sirens and the people Above who want to kill them. And most of all, anger at the long-ago, greedy people who brought us to the point where the only way to survive was to Divide. Those people used up everything. They wasted the trees; they burned through the air. They didn’t care, or if they did, they didn’t care enough, and now we’re the ones paying the price of their extravagance.