Disclaimers: Don't own Dragon Ball Z, so NAAAAAAHHHH! $_$
Author's Note: This is Dragon Ball Z but it's an AU so you may not recognize all the characters.
Prologue: A Brief History of the Galactic War
The Cold Empire is a ruthless group that purges, trades, conquers, and annexes other worlds. The Saiyan-jin were a species not much better. Born warriors with great power and three distinctive features: their wild black hair, their ebony eyes, and their brown furred tail. Their leader, King Vegeta, sold their services as mercenaries to the Cold Empire hoping that it would keep King Cold and his families interest on other planets. He was wrong. Dead wrong.
The Saiyans have this ability to increase their power whenever they fight, especially if their greatly injured and then recover. Because of their own inborn ability, King Cold began to fear them and the potential they had to destroy everything he had created. He secretly dispatched his son Frieza to destroy the planet Vegeta-sei and take care of the potential problem in one fell swoop.
It was fortunate for the Saiyan-jin that one of their kind had been cursed, on a purging mission, with the ability to see the future. The saiyan, Bardock, warned them of the danger, but King Vegeta was too stubborn to listen. His teenage son on the other hand, Prince Vegeta was much wiser than his father and followed Bardock's advise. He, Bardock, his bodyguard Nappa, and the rest of the Saiyans that followed him left the planet. Vegeta-sei was destroyed a week later.
They settled on the mainly unknown planet Ran-sei, where most of the experiments of the Saiyan enslaved Pulli-jin scientists took place. There the scientists worked day and night to come up with a way to increase the present population of depleting Saiyans. They eventually developed a process that could change another species into a Saiyan. The only problem was that there was a requirement of factors in a subject that was susceptible to the changing process. With this as his only choice to prepare an army, Prince Vegeta sent out scouts to locate acceptable subjects….