The motif of mistreatment
In many ways, Precious's story is a response to mistreatment. Her parents are symbols for mistreatment (see below) but also, there is the judgmental principal who expels Precious without making sure he understands her situation correctly. There are the teachers who treat Precious like an idiot, often in front of others, and then there is the student body who often bullies Precious for her extreme obesity, her dark skin, and her social anxiety.
The hateful, jealous mother
This is the figure sometimes referred to as the "Anti-Mother," because although Mary is Precious's biological mother, she represents the opposite of love and support. A mother can either represent life or death because sometimes, as Mary illustrates, a mother can become possessed by jealousy against her own daughter. Then, instead of giving Precious the parental guidance and support that she should, she ends up abusing Precious in her own way. Typically, she verbally assaults her daughter and sometimes, she will take out her anger and frustration on her daughter in the form of domestic violence.
The evil father
There is an antichrist in the novel, an instance of someone committed completely to evil. It seems that Mary, Precious's mother, is mentally unstable (maybe from this evil's father's abuse?), but the father seems to know exactly what he's doing. His attraction to Precious originally comes because he is a deviant. He enjoys the wrongness of his raping his own daughter, and then, as she grows, he continues doing it, even when she's extremely overweight. The reason? Because he's extremely evil and he is specifically dedicated to hurting others in any way he can. He represents malice. Precious has some unfortunate circumstances in her life as it is, but this father represents the additional damage that malicious people have caused her.
The Messiah figure, Ms. Rain
To say Ms. Rain is a "Messiah" figure is not a religious statement exactly, rather it's just a common literary technique for seeing the role that she serves for Precious. Because she met Precious where she was, and because she empowered her, taught her about herself, and elevated her to a place of honor (when Precious shares her poetry, the class is amazed), therefore, Ms. Rain is like a savior to Precious. And just like the Jewish concept of "Messiah," Ms. Rain transforms Precious just by loving her unconditionally. This love is all Precious needed.
Precious's relationship to poetry
The fact that poetry appears in the novel is an important aspect of the work because it helps illustrate the manner by which this fictional story might have been true in part for Sapphire, the author. Precious responds to her unspeakable difficulties in life through her poetry, which is kind of like art theory. The theory here would simply be that art is part of how humans cope with life's suffering and cruelty.
