Smith is a computer program with a particular purpose to serve within the Matrix. When programs die in the Matrix—as the Keymaker does, for example—they are deleted because they have fulfilled their purpose. When Agent Smith fights Neo at the end of The Matrix, something unexpected happens to him. His program evolves or becomes corrupted, and increasingly Smith finds himself at odds with the Matrix world, where all the other Agents remain at ease. He is a program, but somehow he also demonstrates an evolution of character and purpose.
Hugo Weaving portrays Smith as a confused, complex entity. Smith is a program, but he also seems to possess human qualities. We see his desperation, for example, when he faces the Oracle and tries to figure out what she knows and how she knows it. Smith’s style of speech evolves as the trilogy progresses. Initially, Smith is smug, slow, and methodical in his questions, assured that whatever programs he is a part of will run smoothly. Slowly, though, doubt creeps into his voice, and his facial expressions become less controlled. He shows anger. The tone of his voice grows more varied. At crucial moments, Smith takes off his sunglasses and reveals his eyes. Smith blurs the line between man and machine, and though ultimately humans prove more powerful, his resilience suggests that victory was never certain, and that machines have more influence and potential than it might seem.