Erik is motivated by a desire for power and control. It is evident that Erik suffered from intensity in anger when he was younger, evidenced in how he treated Paul and blinded him in the most savage of ways. At the same time, Erik's success as a placekicker helps to feed his need for control and power. He is pampered by his parents and uses his position as a gifted athlete to evade much in way of responsibility. His role in the neighborhood break- ins helps to drive his desire for power and control. The ending in which he is left awaiting arrest for his role in Luis's death is a reflection of how his motivation for control and dominance has a sad ending.
Part of his motivation can be seen as wishing to exert pride upon anyone and everyone. His use of derogatory language towards Luis and the way in which he is able to manipulate his parents' love comes from a source of pride in himself. Certainly, pride becomes linked with the demonstration of power and control that is so much a part of his characterization. In the end, this becomes what motivates him as a character in the novel.