The Karfelon known as The Borad began life as a scientist of the planet Karfel named Megelen, who was encountered in an as-yet unrecorded adventure by the Doctor. (The Karfelons used Borad a title, like President, rather than a name, however, when Megelen took power he referred to himself only by his title.)
During his first visit, the Doctor exposed Megelen to the ruling Council for unethical experiments on Morloxes, large reptiles indigenous to Karfel, and the chemical Mustakozene-80, which has the ability to fuse together different tissue as one creature.
After the Doctor left Karfel, Megelen was apparently able to continue his experiments, but was accidentally fused with one of the Morloxes via Mustakozene-80, becoming half Morlox and half Karfelon. He believed that his intelligence and longevity had increased.