The five characters in question are all, broadly speaking, antagonists who stand in the way of more heroic and sympathetic characters, presenting obstacles for them to overcome either emotionally or practically. Of the three antagonists from The Thorn Birds, Fiona Cleary is the one who fits this pattern least well, since one might argue that she is principally bitter and unhappy rather than villainous. However, her treatment of Meggie, while not motivated by malevolence, has similar effects to Luke O'Neil's tyranny and Mary Carson's cynical manipulation. Mary is the most intentional and spiteful of the three characters, but they all have strongly negative effects on those around them.
Aseef in The Kite Runner is clearly not only an antagonist, but an exceptionally despicable character, who admires Hitler, exploits the weak, and rapes Hassan. He finds his natural place in the Taliban, of which Rasheed in A Thousand Splendid Suns is also broadly supportive. Rasheed is a toxic influence on the lives of both Mariam and Laila. Though he is not such a thoroughgoing sadist as Aseef, his abuse of power on a domestic level is more thoroughly explored. In this sense, he closely resembles Luke O'Neil, who exercises a similar tyranny over his family in The Thorn Birds.