Who was Hassan in the Kite Runner most like in A Thousand Splendid Suns and The Thorn Birds?

It can be argued that Hassan is most like Mariam in A Thousand Splendid Suns and Dane O'Neill in The Thorn Birds.
Certainly, Hassan's innate incorruptibility, humility, generosity, and loyalty are traits shared by both Dane and Mariam. In The Kite Runner, Hassan retains his loyalty and affection for Amir, despite the latter's betrayals. Years after he is forced out of Baba's home (and after Baba's death), Hassan consents to return to Kabul with Rahim Khan.
There is no hint of anger, bitterness, or malice in Hassan, even as he decides to give up his idyllic life outside Bamiyan for Rahim Khan's sake. Hassan even offers to help Khan tend to his former employer's home. In discussing Amir with Rahim Khan, there is only affection and kindness. When Hassan and Farzana (his wife) reach Kabul, Hassan refuses to stay in any of the rooms in Baba's home. He chooses the hut in the backyard where he was born. When questioned by a bewildered Rahim Khan, Hassan merely replies that it would be a disrespect to Amir for him to take up residence in his former friend's childhood home.
When the tortured Sanaubar, Hassan's mother, finds her way back to Baba's home, Hassan and Farzana nurse her back to health. We must remember that Sanaubar left Baba and Hassan shortly after Hassan's birth. She had rejected Hassan then because of his physical deformity. Despite her past cruelty, Hassan tends to her lovingly and provides her safety and respite in her old age.
Hassan's magnanimity and generosity can be seen in Mariam in A Thousand Splendid Suns. In the story, she opens up her heart to Laila and Aziza, despite her reservations. Mariam acts as a surrogate mother to Laila and a grandmother to Aziza. When Laila decides to flee Rasheed's home, Mariam accompanies her. Both women endure Rasheed's beatings, however, when their plans fall apart. However, the indomitable Mariam courageously comes to Laila's aid when Rasheed threatens to go through with killing the younger woman.
In the throes of unadulterated rage, Rasheed had failed to notice the raised shovel in Mariam's hand. For her part, Mariam had mustered all her strength to bring the shovel down on Rasheed's head. After Rasheed's death, Mariam stays behind to take the blame for his death. Her sacrifice on behalf of Laila, Aziza, and Zalmai is a testament to her depth of character.
In The Thorn Birds, Dane is as close to Hassan's equal as you can get. He is effortlessly sanguine, compassionate, and loyal. Additionally, Dane is inherently ethical, authentic, and sincere. Unlike his father (Ralph de Bricassart), Dane nurses no ambivalence regarding his ambitions: his devotion to the Church and to God is absolute and untarnished by lust for a woman or for anything else the world has to offer.

That's right. I don't want to, ever. Not that I haven't thought about it, or wanted a wife and children. I have. But I can't. Because there isn't enough room to love them and God as well, not the way I want to love God. I've known that for a long time. I don't seem to remember a time when I didn't, and the older I become the greater my love for God grows.

Like Hassan and Mariam, Dane is also unselfish to the very end. His death is precipitated by his gallant behavior in saving two female tourists from drowning. In the last lucid moments before he succumbs to his heart attack, Dane's only thoughts are pure ones.
Hassan's equivalent in The Thorn Birds is Dane, and his equivalent in A Thousand Splendid Suns is Mariam.