Rahadin was one of the dusk elves. He was exiled for refusing to bow down to a prince he saw weak. When the dusk elves declined to pay fealty to King Barov (Strahd's father) Rahadin helped Barov conquer them. Barov then made Rahadin an honorary member of his family.
After Barov died Rahadin fought as one of Strahd's generals. After Strahd's fall from grace a Dusk Elf named Patrina Velikovna tried to marry Strahd but she was killed by her own people. Because the dusk elves deprived him of her, Strahd sent Rahadin to punish them and Rahadin killed all the females so the males couldn't breed.