Angels and Demons...Once upon a time...
Long ago in a Galaxy far far away...
There were two habitable planets revolving around a single sun. The two planets were named Heaven and Hell. The life forms that evolved on these planets were notably different. Hell was in a rotation closer to the sun and was therefore much hotter than Heaven. Fiery and barren, it was a very unforgiving planet. The need to survive made the creatures that evolved there, cannibals and scavengers as well as hunters. Those born on Hell were a breed of warriors, fierce, and red skinned. They had bat like wings and horns that grew from the sides of their heads. Their culture was one of strength, and cunning. They believed that only the strong should survive, that anyone that could be killed should be killed. They were a tenacious breed, tough and difficult, much like their planet. When one was killed the victor would take all that the vanquished had accumulated as their own. Honesty was not a valued trait as many victories were had through the use of lies, and treachery. This breed came to call themselves Demons.
On Heaven, the beings were graced with a much more benign atmosphere. A climate that supported life of many varying types. It was a world rich in vegetation, and wildlife. Plants and animals abounded, water and all other resources that they needed was theirs for the taking. They too were a warrior breed, and predatory but one that learned the benefits of cooperation. They worked together as well as alone and their civilization grew to a vast and great level. They progressed in the ways of science and of natural law. One day they discovered the ways of spaceflight and of interstellar travel. These beings were of various skin tones, some had feathered wings like those of birds, some were without. The differences in their own features and traits made them more open to new and different things. More accepting of and supportive in their dealings and beliefs of others. They accepted new ideas readily and this open mindedness made their evolution in art and science grow in leaps and bounds.
One of their first stops in the exploration of their solar system was the planet known as Hell. There the Angels, as they called themselves, discovered the very primitive and violent civilization of the Demons. The Angels were posed no threat by the Demons because of the vast technological advantage their species had over the Demons. They were convinced that they could teach and help the Demons evolve to a higher place. The Angels found the demons to be very docile and attentive after being beaten in combat. They found the Demons to be actually very intelligent and eager to learn. Knowing they could teach the Demons a better way to live and exist they began doing that very thing. The Demons, true to their nature, played along once they discovered that the Angels were un-beatable. As they were taught by their very nature, that which could not be killed must be obeyed. They grew in understanding of science and warfare until one day many generations later they finally had learned enough to be able to fight against and defeat the angels.
Satan, a great, wise and very powerful Demon was the first to rebel and take over one of the angels ships. The Angels were taken by surprise because they truly believed that the Demons had put away their old ways of violence for the sake of violence.
A great civil war ensued, both sides grew in the knowledge of warfare, and of each other. The only thing that grew faster than this knowledge was the hatred of these two races, the once allies and brothers.
Satan returned to Hell and took over, killing all that stood in his way. The Angels who were on the planet fled or died. Constant attacks from Hell on Heaven caused the Angels to eventually destroy the planet and scatter the occupants to the vastness of space. Some Demons during the times of tutelage did truly evolve and become a part of the civilization of the Angels. Some were still playing along, those that were found to be merely biding their time, waiting to exploit some weakness, were sent to Hell and barred from ever again setting foot on planet Heaven. After the destruction of Hell in the home solar system, the Demons found and colonized another planet much like the Hell of old. Of course they named the new planet Hell as well.
As the two waring species continued to evolve and progress in the ways of science and natural law. They grew in knowledge and understanding. Each being pushed by the survival instinct inherent in them both. They discovered terrible and horrific ways to kill one another, and they also discovered the secret of immortality. By combining themselves with millions of microscopic robots, they called nanites. These nanites were a parasitic kind of machine that fed off of the host body, keeping the host body in a state of perfect health. The regenerative properties of the nanites could bring the badly wounded back to a state of perfect health. Death was only caused by the destruction of the entire body, if the nanites didn't have enough tissue left to remake the body then the body died. The nanites died along with the host body.
The two races came to the conclusion that neither could be defeated by the other and a strange kind of truce came into play. Any world claimed by one of the two races was left alone by the other race. Only worlds in positions of importance to both races were still fought over. These worlds however were not to be inhabited by either race and only through indirect contact could the development of any species on these planets be influenced. At some point in the development of the species inhabiting these contested worlds a choice was to be made by these worlds inhabitants. The choice once made was irreversible and incontrovertible.
The Demons soon came to find that the species of these planets never willingly chose to become enslaved to the indefeatable Demons so again as is their nature they resorted to lies and deception. The Angels came to use the truth as their weapon of choice.
In the Fullness of Time...
A planet called Earth was discovered. The Angels and Demons both explored the world and the native inhabitants of this planet. Once a dispute for the world was established both the Angels and Demons withdrew from the planet. The Angels and Demons had both developed the ability to communicate telepathically. Some of the advancements of both species were of the magical type. The ability to summon great mystical powers was the reason both species had to form the truce.
The similarities of this world called Earth and the Angels home world made it especially desirable to both species. The Angels because it brought them nostalgia, the Demons because of the desire to destroy it and hurt the Angels with that destruction.
Perhaps at some point one of the Angels spaceships orbiting the planet was hit by something and destroyed. Leaving stranded on the surface three explorers who had gone to the planet. Perhaps a Robot took some genetic material from one of the crew on the mother-ship and escaped to the planet as well...
But that is another story... What-If-Jesus-was-an-Alien