Father Ralph De Bricassart is quite the anti-hero. While he has positive qualities, he isn't a completely sympathetic character. In essence, because he finds himself steadfastly conflicted between the Church and his lust for Meggie, we get the feeling that he doesn't deserve Meggie's adoration.
It is Father Ralph who chooses to deny Meggie her rightful inheritance of thirteen million pounds in order to pursue his ambitions within the Catholic Church. At the same time, he consummates his love for Meggie and satisfies his lust without making a commitment to her. His excuse is that he was born to be a priest and that he owes the Church his complete allegiance. To salve his conscience, he makes sure that the entire Cleary family receives generous yearly incomes. When Meggie's son dies, it is Father Ralph who uses his influence to bring Dane's body home for burial. Father Ralph is a multifaceted, complicated character. He is neither a gentleman nor a complete cad.
In The Kite Runner, the character who best corresponds to Father Ralph De Bricassart would be Amir. In the story, Amir betrays his cowardice when he chooses to leave Hassan to his fate at Assef's hands. After Hassan's rape, Amir further torments his servant companion by accusing him of theft. Because of his despicable actions, Hassan and his father, Ali, have no choice but to leave Baba's home and employ. This is an egregious betrayal, and Amir knows it. To redeem himself, he agrees to retrieve Sohrab, Hassan's son, from the clutches of the Taliban. However, it is only after Rahim Khan's fantastic admission about Hassan's paternal heritage that Amir sees his true responsibility.
At this point, we are interested in whether Amir will manage to redeem himself in his eyes and in ours. Unfortunately, it is Sohrab who has to save Amir from being beaten to death by Assef. Considering that it was Amir who had originally set out to save the poor boy, this doesn't speak well of our hero. Luckily for Amir, Sohrab's skill with a slingshot allows them both to escape Assef's murderous fury. Even in his quest for redemption, Amir doesn't quite succeed. He's mentally weak and easily intimidated by bullies.
In A Thousand Splendid Suns, the character who best corresponds to Father Ralph would be Laila. She is a complicated character who both inspires our sympathy and our judgment. When Laila discovers that she is pregnant with Tariq's baby, she consents to marry Rasheed in order to pass off the older man as Aziza's father. In this, Laila exemplifies a Machiavellian cunning which rivals that of Father Ralph's. Later, Laila has to leave Mariam behind to take the fall for Rasheed's death. Although she had no choice, Laila knows that she left an innocent woman behind to face death without comfort and without hope.
Certainly, your thoughts may vary regarding the characters that best correspond to Father Ralph, but I hope that the suggestions above are helpful.