Brandon put both hands over his face and wept, standing right there in the corridor, and his mother came out of the waiting room and held onto him, and the two of them stood in the hallway and cried until the crying turned, somewhere in the middle, into something like laughing.

That first night, Sierra couldn’t talk. There was an oxygen mask over her face and tubes running everywhere and a monitor over the bed keeping its steady, ordinary, miraculous time.

But when Brandon sat down beside her and took her hand, she turned her head, and found his eyes, and tapped out a slow, deliberate rhythm against his wrist with two fingers — tap, tap, tap — telling him, in the only language she had left that night, that she was all right.

Her recovery was long and it was not easy. There were months of physical therapy, a wall of medications, good days and frightening ones. But three months after the surgery, Sierra walked out the front doors of the hospital under her own power, into the daylight, and did not look back.

Six months after that she went back to school. And a year after the surgery, on a bright cold Saturday, she ran a local five-kilometer race — slowly, near the back, walking part of it — and crossed the finish line on her own two feet with her arms in the air.

Brandon was waiting for her there, and he was crying again, because it seemed he was going to spend a good part of his life crying now, and he gathered her up in a hug.