Daniel has lived under Roman oppression all his life. Jews like himself are under Roman rule, and are forced to abide by confiscatory taxes and unfair laws that make them third-class citizens. While young, Daniel did not fully understand these laws. However, he had them thrust upon him long before he was ready, when his father and uncle were killed:
"But my uncle had lost his head and tried to fight his way out, and the soldiers would not let him off. They said he would go to the quarries to work off his debt.
So my father ... and four others hid in a cornfield and waited till the Romans started for the city with my uncle, and then they attacked. Of course they were all captured. ... They crucified all six of them, even my uncle..."
(Speare, The Bronze Bow, Google Books)
After this, Daniel is sold into slavery to the local blacksmith. Because of his losses and his adolescent feeling that unfairness should be fought against and beaten, he runs away and joins with Rosh, a bandit in the hills. For the next several years, Rosh instill a deeper and deeper hatred of the Romans in Daniel, knowing that he can manipulate Daniel to lie and steal for him; Rosh knows that Daniel is committed to the cause of freeing Israel, and so reinforces Daniel's hate for his own ends. It isn't until Daniel meets Joel and Thacia, and experiences his own family life again, that his emotional health starts to improve.