It all started the way it all started. There was a tiny matter. And then it exploded.

Fig had gotten an A on her Big Bang diorama, so even though her fifth-grade science unit had been vague on a lot of details, she knew enough to know they were in really deep trouble.

Right before what happened happened, back when they were a hot, tiny ball of dense singularity, Fig’s family was just a family. Maybe people would guess that Fig and Jack left school in a limousine to eat lunch at a fancy restaurant every day and rode horses in their backyard and lived in a giant mansion, but really they went to school in a normal car and ate lunch in the cafeteria and lived in a regular-sized house.

Fig had never ridden a horse.

Fig’s mother was famous, but she wasn’t horses-in-your-backyard famous. And Fig and Jack didn’t go to summer camp. Fig’s therapist made her keep a list of things that scared her, and it included roasting marshmallows over a campfire, singing songs around a campfire, and scooting close to a campfire to avoid mosquitoes. Since most camp activities seemed to involve fire, Fig had nowhere to learn to ride a horse.

It was strange, given what had happened to them and given that they were twins, that Jack didn’t mind fire. He also didn’t mind other things people might not like about camp, like never taking a shower and whatever bug juice was. But Fig knew Jack wasn’t sad about not going to camp and staying home with her instead. She and her brother didn’t always like each other, but they did always like to be together rather than apart.

Being apart was on both of their lists of scary things.

Scientists—or at least Fig’s science teacher—did not know what caused the Big Bang, but they did know that billions of trillions of unlikely factors had to be exactly right for it to occur. If it had been fall or winter or spring, Fig and Jack would probably have been at school. If Fig hadn’t been afraid of fire, they would probably have been at camp. If she didn’t have to share a phone with her brother or even if it had been her turn or especially if Fig had been a different kind of ten-year-old, she might not have been reading the newspaper that morning. But none of those ifs came true. So conditions were unlikely, but unfortunately perfect, for their entire lives to explode.