Harvey's purpose is threefold: he is to unlock the wormhole knowledge stored somewhere in Crichton's brain, protect Crichton's life until Scorpius manages to retrieve the chip, and prevent Crichton from hurting or killing Scorpius. Harvey also has the ability to stop Crichton's brain functions for a short time, making him appear dead. He can control Crichton's memory and nervous system when the chip is in place, which he uses to hide his presence from Crichton. Eventually, the chip becomes strong enough to completely dominate Crichton's mind and body. Even after the chip is removed, Harvey is able to exert limited control over Crichton. After Scorpius reprograms him, Harvey has some type of mental link to Scorpius that allows Scorpius to track Crichton down after John is revived from his crystallization by the Eidelons. Harvey contains much of Scorpius' knowledge and intellect.