What conditions led to Reuven's hatred of Danny in the first two chapters of The Chosen? What factors brought about the discovery of their friendship?

The boys are both Jewish, but their families practice Judaism differently. Another condition would be the softball game itself.... a cometition between schools and individuals. When Danny injured Reuven during the game, he shows his concern by becoming a part of Danny's recuperation..... thus, the boys find common ground and a friendship.