My daughter Mia is not my biological child.

I want to tell you that up front, the way I’ve had to tell it a hundred times to nurses and school offices and, once, to a very confused woman at a passport office who couldn’t understand why my last name and my daughter’s history didn’t line up on paper. Mia is my late sister’s daughter. And she is, in every way that has ever mattered, mine.

My sister was named Dana. She was two years younger than me and about ten times braver, the kind of person who filled up a room the second she walked into it. She got pregnant young, and the man was gone before Mia was born, and Dana didn’t care one bit. “I don’t need him,” she told me, glowing, huge, sitting on my couch with her feet up. “I’ve got you, and I’ve got this baby, and that’s a whole family right there.” She was right. For four months, it was.

Then there was a car. A rainy night. A phone call at 2 a.m. that I still hear sometimes when the house is too quiet.

And just like that, I was thirty years old, unmarried, and holding a four-month-old baby who had my sister’s exact eyes.

Nobody handed me a manual. Nobody sat me down and asked if I was ready, because there was nothing to be ready for, there was just Mia, warm and howling and needing to be fed, and me, the only person left in the world who was going to do it. Our parents were gone by then too. There was no one else. So I did what you do. I took her home. I figured it out. I became her mother the way you become anything real, without ceremony, one impossible day at a time.

I raised her alone for six years.

Those were hard years, and I won’t pretend they weren’t. I worked and I scrambled and I learned how to braid hair off a video at midnight and how to soothe a fever and how to be two parents at once. But they were also the best years I’d had, because that little girl was the light of my life. She called me Mom before she could really talk, and I never corrected her, because what would I have corrected it to? I was her mom. Dana would have wanted that. I felt her blessing in it every time Mia said the word.

Then, when Mia was six, I met Thomas.