Aristotle and Dante Discover the Secrets of the Universe by Benjamin Alire Saenz

Best-selling classic young adult novel that's a real charmer.
 
Aristotle is an angry teen with a brother in prison. Dante is a know-it-all who has an unusual way of looking at the world. When they meet at the swimming pool, they seem to have nothing in common. But as the two loners start spending time together, they discover that they share a special kind of friendship--the kind of friendship that changes lives and lasts a lifetime. And it is through their friendship that Ari and Dante will learn the most important truths about themselves--and about the kind of people they want to be.