Slavery imagery
The novel's opening is a depiction of a slave's life, but instead of slavery, the bond is familial. However, when later, Erendira tries to escape (peacefully, at first), the officer's of the law bring her back to her horrifying life. This imagery is reminiscent of the slavery of black people in the Western world, especially the way the government protects the tyrant's rights to exploit an innocent, helpless victim.
Violation imagery
The novel explains that the girl was all alone, with the dusty air of the old house, and then the grandmother entered and everything changed. This sets up the basic structure of the plot, that the grandmother will represent the violation of the girl's safety, not the protection of it. The violations turn into rapes, and the imagery of being violated continues.
The imagery of murder
The novel depicts three attempts to murder the grandmother. First, it describes an attempt to poison her with arsenic, which fails. Then it describes a description of an explosion, which also fails to kill her. In the end, there is no other way to perform the murder than through outright violence. Ulises brutally murders the grandmother by stabbing her repeatedly. This imagery is designed to indicate the breach of innocence that Erendira is subjected to, because they indicate her willingness to murder in cold blood.
The imagery of gold
When Erendira kills her grandmother, she earns spoils instead of an inheritance, and the novel is careful to describe the beauty and value of the gold and jewelry. She's like a pirate with a bounty.