The creation of villainy
The readers are not directly exposed to Mala's suffering. First, they experience the life that Chandin experiences as a first-generation immigrant and religious convert. Raised by a minister, he is often frustrated by his call to be hyper-moral. What is the reward for his decision to be good? Nothing but disappointment, he feels (because he is insanely entitled). When his true love denies him to be with his wife (whom he married as a consolation), he plays the victim for life, giving his life over to alcohol and sexual deviance.
The dead patriarch
Mala's character is fully exposed when she lapses mentally into a delusion. She thinks that Otoh is his father, Ambrose, and she wants to talk to Ambrose because they were going to be together and fall in love before her father found out about them and violently raped her and threatened her life, torturing her emotionally and physically so that she would not attempt to be with Ambrose. When she thinks Otoh is Ambrose, she excitedly reveals that she has murdered her evil father to avenge their lost love. This symbolizes the basic shape of her insanity; she is only insane because her own father brutally violated and dehumanized her her whole life.
Insanity as a symbol
Insanity is therefore its own symbol in the text, because it is not insanity in a vacuum. In fact, one could say that Mala symbolically represents the archetypal victim while her father is an archetypal villain. In the end, Mala asserts a kind of divine worth by assassinating her tyrant patriarch. By taking his life, she asserts that the suffering he caused was ethically unacceptable for human beings, and for treason against her inherent worth, she feels entitle to harm him. This is a poor argument for violence and it should be noted that she is guilty of murder, but still, the death can be easily shown as a consequence of Chandin's own behavior.
The domain of childhood
One reason why a reader might try to forgive Mala is to remember that her violation took place within the domain of childhood. Children are experiencing inherently dependent and psychologically fragmented points of view as they grow through experience. By remembering Mala's inherent helplessness as a child, a reader can also see that Mala's choices were severely limited by the chronic abuse and the way that shaped her expectation of reality. For her, life was a torturous prison of rape and betrayal by her own father.
The fire salvation
Because he understands that Mala (whose name is Latin for bad) is not necessarily guilty of her own actions, Otoh acts in the narrative as a redeemer who purges her guilt by fire. She survives the furnace and loses everything she ever owned, along with her free will, but she is spared the consequences of her action because Otoh knows her point of view well enough to forgive her. This is a symbolic redemption. Also, she mistakes him for his father Ambrose, which means that she is treating him as a kinsman. He is an archetypal kinsman redeemer.
