"Tadaima."
"Okaeri."
He puts his bag down and peeks in through the door, his eyes falling on the shape of a teenage girl sitting cross-legged on the floor. Her response to him is automatic by now, a few simple syllables uttered without thought, but each time he hears it there is the faintest fluttering of joy in his chest. He still, even now, isn't used to being greeted when he comes through the door.
"Hey," she says, and leans over to watch him change his shoes, "did you finish that math assignment?"
"Ah... yesterday."
"Let me borrow it. I'm no good with fractions." She wrinkles her nose, as if the very thought of non-whole numbers is revolting, and there is another little movement within his chest, as if everything she says or does is capable of making his heart do cartwheels. And really, he thinks as he steps inside, that's becoming the truth.
He slides his bag to her and promptly collapses by her side, stretching out on the floor on his back. She gives him a curious glance, but she has already dismissed his behavior as normal, and her hands are busy with the retrieval of his homework. He watches her search for the right notebook and thinks to himself that this acceptance, this casual acknowledgement of normality, is the best thing in the world.
This, he decides, and smiles as she opens his math notes, is home. This is where he wants to be right now, beside the girl he has risked life and limb to save, watching her copy down the answers to their homework. It is ordinary and trivial and it is the most beautiful thing he has ever seen.
They are young, so young, but he knows already that he wants this for the rest of his life. This is where he wants to be. He sighs and she smiles, and he knows that he is home.