Cat's Eye is, at its core, a story about self identity and the struggle that sometimes exists between personal autonomy and needing the acceptance of others. The story's protagonist, Elaine, is introduced as a grammar school-aged girl who moves to a new area and befriends two local girls. The following year, another new girl, Cordelia, enters their group and upsets the entire dynamic. The two local girls who were previously friends with Elaine change their attitude and start bullying her, with Cordelia serving as ringleader. Gradually, Elaine's self-confidence erodes and she struggles with finding the strength to stand up for herself while still pining for their acceptance.
The story later picks up with Elaine in high school. The dynamic again shifts, as Elaine has grown much stronger through her faith. She reestablishes her friendship with Cordelia, but in an effort to exert control over her life, begins taunting and bullying Cordelia in much the same way she was bullied in grammar school. The irony is how uncharacteristic this is to someone allegedly following the tenets of Christianity; however, it is clear Elaine still has not been able to reconcile her sense of self with her desire to maintain healthy relationships with others. She actually feels a bit of joy at Cordelia's mental implosion as Cordelia struggles at school. In this way, Cordelia still has control over Elaine, albeit inadvertently, as Elaine is unable to act in a genuine fashion because she can't let go of their past.
As adults, Elaine and Cordelia meet again. Cordelia has now been committed to a mental institution and is desperate for Elaine's help. Again, feeling the need to exert control over their relationship, likely as recompense for their history as children, Elaine refuses. In a similar way that Elaine struggles to free herself from Cordelia, Cordelia must also free herself from Elaine. They must learn to survive without each other and will likely be better people for it. As it turns out, Cordelia escapes the institution without Elaine's help, and Elaine never sees her again. By the permanent severing of their relationship, they can both focus on being themselves instead of vying for power over the other in a relationship construct that, by all accounts, was unhealthy for both.