Danny and Reuven view each other as being different. What does danny and reuven have in common?

Both of their fathers are respected leaders in their communities--Danny's father is the tzaddick of the Hasidic group and Reuven's father is a respected teacher and scholar who becomes a prominent voice in the push for Zionism.

Both Danny and Reuven are excellent students--Danny is blessed with "total recall" and is respected by his father's followers as a Talmudic scholar already at a young age, and Reuven proves that he is an excellent student through his diligence. Both of them are influenced by the circumstances and environment of World War II. Assimilation changes their world views during the course of the novel.