“Psh,” I say. “Don’t even. We worry about each other. That’s what sisters are for. Besides.” I squeeze her hand. “You also make me happy. You like your weird little sister’s pictures on Instagram and send her funny selfies and appreciate the random things I bring you, like bird feathers. I mean, you know better than anyone that sometimes I’m helpful and sometimes … not, and sometimes I probably push things too hard, trying to make them exactly what I … But anyway, the point is … the point is, my life wouldn’t have treasure hunts without you.”

She gives a laugh that’s very close to crying. “Not so much on this trip. I haven’t been my … I’ve been having a hard time and you get the worst of that.”

“Heck,” I say, “I’m the one who just, like, volcanoed at you.”

She gives me her wide-eyed look, but she’s grinning. “You did, didn’t you? That was … unexpected. Honestly kind of impressive. I didn’t know you had it in you.”

“Oof, I didn’t either,” I say, guilt splashed across my face. “And, Ruth?” I pull her close until I’m holding her forearm tight against me, carefully letting the IV cords flow out from between us. “You never, ever, ever, need to apologize for being sick.”

I think of the whole pile of things we’ve done together, been together, and while we sit on the bed, I feel the truth of those words settling in me like an anchor on the ocean floor.

“Olivia?” Ruth says. Her throat bobs again. “You do matter, you know.”

“I know. I’m sorry for what I said. I—”

“No, listen. You’re my … my no-filter person.” She sniffs and wipes a strand of plastered hair from her forehead. “My free person.”

It takes a moment, but her words breeze in and fill me, like oxygen filling empty lungs. At least in this moment, the constant, anxious buzzing at the back of my mind is still.

I say, “Because I’m your barnacle little sister and you know you’re stuck with me for life no matter how much I bug you.”

She leans back into the bed and sighs like her whole body is exhaling. “Something like that, yeah,” she says. The grin she gives me is exhausted but utterly real.

It’s strange how normal it feels talking to Ruth right now. Like some wide, deep river was between us before and we tried shouting across to each other but couldn’t really hear. And now we’re in the middle of the river, both of us.

I watch her lying there, her eyes closed, and I think, If humans weren’t so drownable, we’d never have invented sailing ships and submarines.

“Actually, I changed my mind,” Ruth says. “I could use some water.”