"Doe" was one of many who represented the next evolutionary step for Zalkonians as they shed their corporeal forms and became beings of pure energy. "Doe" fled his homeworld due to persecution by Zalkonian authorities, who viewed the evolution of individuals in their society as a threat. He crash landed on a remote planet.
When he was discovered by the Enterprise, "Doe" had several life-threatening injuries and Dr. Crusher initially believed that he would not survive, but "Doe" demonstrated tremendous recuperative powers and became well again. While recuperating, "Doe" began to manifest strange abilities, including emanations of energy and the ability to heal wounds by touch, and even to restore life from the dead. However, the injuries "Doe" had sustained included a memory loss which prevented him from explaining his abilities, or even why he had been in the escape pod. "Doe" began to experience bouts of severe pain. When Crusher reported that his cell mutation had increased, he feared that he could become dangerous to the crew, and he decided to leave, and attempted to steal a shuttlecraft. When Worf tried to stop him, "Doe" generated a large flare that unintentionally killed Worf. Worf had a broken neck and no vital signs, but "Doe" healed and revived him by just touching him.
The Zalkonians eventually found "Doe" aboard the Enterprise-D and the Zalkonian Commander Sunad demanded his return as a criminal to face the death penalty. When Captain Picard refused, Sunad, who enforced a genocidal program that almost wiped out all Zalkonians exhibiting this evolution, attempted to take "Doe" by force, using an energy beam that began suffocating the crew of the Enterprise-D. However, "Doe" was able to heal the crew and dissipate the beam. He brought Sunad onto the Enterprise-D and explained to Picard that his species was on the verge of an evolutionary change. "Doe" tried to convince Sunad that what was happening was not evil and that people like him were not a threat. Sunad would not accept this, and was returned to his ship.