Is Amir in The Kite Runner more like Father Ralph or Luke O'Neill in The Thorn Birds?

Amir, the protagonist of Khaled Hosseini's The Kite Runner, is a young Pashtun boy who witnesses the beating and rape of his friend, Hassan, but makes no effort to intervene. Amir eventually leaves Kabul after Soviet forces begin to intervene in Afghanistan. Amir only returns to his homeland many years later in order to rescue Sohrab, the orphaned son of Hassan, as an attempt to find "a way to be good again."
Thus, one might argue that Amir is most like Father Ralph in Colleen McCullough's The Thorn Birds. Amir, although unlikable and cowardly throughout much of the novel, is not a proactively aggressive character (unlike Luke O'Neill, who marries Meggie only to cruelly neglect her and steal her wages and savings).
Rather, Amir's greatest downfall is his passivity and weakness. Father Ralph suffers from this same flaw; he attempts to avoid conflict and "sells out" by accepting Mary's inappropriate bequest so he may gain favor within the Catholic Church. Ralph consciously makes this choice despite knowing that it will hurt Meggie, much like how Amir chooses to betray Hassan by failing to step in during his physical and sexual assault. 
Ralph also frequently violates his own principles and fails to uphold his integrity. He breaks his vows of chastity by impregnating Meggie and failing to acknowledge his parenthood; he values status over his own family. Similarly, Amir also chooses a comfortable existence over the lives of those who are important to him. After Hassan is raped, Amir frames the boy for theft in order to get him to leave the household. This betrayal becomes even more disturbing when we discover at the end of the book that Hassan was actually Amir's half-brother. 
Ultimately, although Amir is not as "active" or blatant of an instigator as Luke, his behavior at the beginning of The Kite Runner—like Father Ralph's own passivity—is perhaps more insidious than Luke's. The secrecy of his action (and inaction) allows him to avoid public responsibility, even if it can't save him from the burden of guilt.