Paolo Giordano - The Solitude of Prime Numbers

"Go on, or you'll be late. Remember to thank his parents," she said.

Then she turned to Mattia.

"Take care of your sister. You know she shouldn't eat junk."

Mattia nodded. Adele kissed them both on the cheek, Michela for longer. She tidied Michela's hair under her hair band and said enjoy yourselves.

On the way to Riccardo's house, Mattia's thoughts kept time with the Lego pieces, which shifted back and forth inside the box like the tide. Michela, tagging a few feet behind him, stumbled as she tried to keep up, dragging her feet through the mush of dead leaves stuck to the pavement. The air was still and cold.

She's going to drop her potato chips on the rug, thought Mattia.

She'll grab the ball and she won't want to give it back.

"Will you hurry up?" he said, turning to his twin sister, who had suddenly crouched down in the middle of the pavement and was torturing a long worm with her finger. Michela looked at her brother as if seeing him for the first time in ages. She smiled and ran to him, clutching the worm between her fingers. "You're disgusting. Throw it away," Mattia ordered, recoiling.

Michela looked at the worm again for a moment and seemed to be wondering how it had ended up in her hand. Then she dropped it and launched into a lopsided run to join her brother, who had already walked on ahead.

She'll grab the ball and won't want to give it back, just like at school, he thought to himself.

Mattia looked at his twin, who had his same eyes, same nose, same color hair, and a brain that belonged in the trash, and for the first time he felt genuine hatred. He took her hand to cross the street, because the cars were going fast, and it was then that the idea came to him.

He let go of Michela's hand in its woolen glove, instantly thinking that it wasn't right.

Then, as they were walking by the park, he changed his mind again and convinced himself that no one would ever find out.

Just for a few hours, he thought. Just this once. He abruptly changed direction, dragging Michela by an arm, and entered the park. The grass was still damp from the night's frost. Michela trotted behind him, muddying her brand-new white suede boots. There was no one in the park; it was so cold that no one would have felt like going for a walk. The twins came to an area with trees, three wooden tables, and a barbecue. They had eaten lunch there once, in year one, when the teachers had taken them to collect dry leaves from which they made ugly table decorations to give to their grand-parents for Christmas.

"Michela, listen to me," said Mattia. "Are you listening?"

With Michela you always had to check that her narrow channel of communication was open. Mattia waited for his sister to nod.

"Good. So, I have to go away for a little while, okay? But I won't be long, just half an hour," he explained.

There was no reason to tell the truth, since to Michela there was little difference between half an hour and a whole day. The doctor had said that her spatiotemporal perception development had been arrested at a preconscious stage, and Mattia understood perfectly well what that meant.

"You sit here and wait for me," he said to his twin. Michela stared gravely at her brother and didn't reply, because she didn't know what to say. She gave no sign of having really understood, but her eyes lit up for a moment, and for the rest of his life when Mattia thought of those eyes he thought of fear.

He took a few steps away from his sister, walking backward to make sure she didn't follow him. Only prawns walk like that, his mother had yelled at him once, and they always end up crashing into something.

He was about fifteen yards away and Michela had already stopped looking at him, engrossed in trying to pull a button off her woolen coat.

Mattia turned around and started to run, tightly clutching the bag with the present. Inside the box more than two hundred little plastic blocks crashed into one another. It was as if they were trying to tell him something.

"Hi, Mattia," Riccardo Pelotti's mother said as she opened the door. "Where's your little sister?"

"She has a temperature," Mattia lied. "A mild one."

"Oh, what a shame," the woman said, not seeming displeased in the slightest. She stepped aside to let him in.

"Ricky, your friend Mattia is here. Come and say hello," she called, turning toward the hall.

Riccardo appeared, sliding along the floor, an unpleasant expression on his face. He stopped for a second to glance at Mattia and look for traces of the retard. Relieved, he said hi.

Mattia waved the bag with the present under the woman's nose. "Where shall I put this?" he asked.

"What is it?" Riccardo asked suspiciously.

"Legos."

Riccardo grabbed the bag and disappeared down the hall.

"Go with him," Mrs. Pelotti said, pushing Mattia. "The party's down there."

The Pelottis' living room was decorated with bunches of balloons. On a table covered by a red paper tablecloth were bowls of popcorn and chips, a tray of dry pizza cut into squares, and a row of still unopened soda bottles of various colors. Some of Mattia's classmates had already arrived and were standing in the middle of the room guarding the table.

Mattia took a few steps toward the others and then stopped a few yards away, like a satellite that doesn't want to take up too much room in the sky. No one paid him any attention.

When the room was full of children, an entertainer with a red plastic nose and a clown's bowler hat made them play blindman's buff and pin the tail on the donkey. Mattia won first prize, which consisted of an extra handful of candy, but only because he could see out from under the blindfold. Everyone shouted boo, you cheated, as he shamefacedly slipped the candy into his pocket.

Then, when it was dark outside, the clown turned out the lights, made them sit in a circle, and began to tell a horror story. He held a flashlight under his chin.

Mattia didn't think the story was all that scary, but the face, lit up like that, sure was. The light shining from below turned it all red and revealed terrifying shadows. Mattia looked out the window to keep from looking at the clown and remembered Michela. He hadn't ever really forgotten about her, but now for the first time he imagined her all alone among the trees, waiting for him, and rubbing her face with her white gloves to warm up a bit.

He got to his feet just as Riccardo's mother came into the dark room carrying a cake covered with candles, and everyone started clapping, partly for the story and partly for the cake.

"I've got to go," Mattia said to her, without even giving her time to set the cake down on the table.

"Right now? But the cake."

"Yes, now. I've got to go."

Riccardo's mother looked at him from over the candles. Lit up like that, her face was full of threatening shadows, just like the clown's. The other kids fell silent.

"Okay," the woman said uncertainly. "Ricky, walk your friend to the door."

"But I've got to blow out the candles."

"Do as I say," his mother ordered, still staring at Mattia.

"You're such a drag, Mattia."

Someone started laughing. Mattia followed Riccardo to the front door, pulled his jacket from the pile, and said thanks, bye. Riccardo didn't even reply, quickly shutting the door behind him to run back to his cake.

In the courtyard of Riccardo's building, Mattia glanced back at the lit window. His classmates' muffled cries filtered out like the reassuring hum of the television in the living room when his mother sent him and Michela to bed in the evening. The gate closed behind him with a metallic click and he began to run.

He entered the park, but after ten yards or so the light from the street lamps was no longer enough for him to make out the gravel path. The bare branches of the trees where he had left Michela were no more than slightly darker scratches against the black sky. Seeing them from a distance, Mattia was filled with the clear and inexplicable certainty that his sister was no longer there.