Rael was a scientist and one of the last five remaining Scalosians. He was attracted to Deela, the queen of the Scalosians. He and the other Scalosian were infertile due to radiation sickness; they also had undergone acceleration in their biochemistry so that for them, hours were like our minutes. The Scalosians hijacked the USS Enterprise in 2268. They planned to use the ship's male crew as a gene pool so their race could continue.
Along with Ekor, Rael installed a refrigeration unit aboard the Enterprise. Rael tried to freeze the male crew of the Enterprise in order to harvest them for breeding purposes. He became jealous of James T. Kirk who Deela had chosen as her consort. He tried to kill Kirk, but was stopped by Deela. Their plan was unsuccessful due to the efforts of Kirk and Spock. (TOS: "Wink of an Eye")