"There are nights when the wolves are silent and only the moon howls." - George Carlin
In all the eons, all the ages, every chapter in evolution, never did anything live up to one event that set it all in motion. Four and a half billion years ago, a planet the size of Mars, now dubbed Theia, slammed into a young Earth. Molten rock spun off far in immediate space, where it would be pulled together, forming the Earth's only satellite, the Moon. This event, the giant impact and the result it had on the history of Earth since then, has changed life as we know it; seasons, stability and perhaps it had been the instigator of life for our world.
However, this project will look at a completely different world, or rather, worlds, for here, Theia (the Mars-sized planetoid that struck Earth, leading to the Moons formation) does not strike the young Earth, and, like fate, gets trapped within the boundary of the habitable zone.
Over the next billion years, both planets experience a dramatic change; life. Starting out as chemicals in a primordial soup, first RNA, followed by DNA formed. Untold generations later, microscopic bacteria, the first true life evolves out of the cluster of DNA. Thus, the stage is set for 7 billion years of life on both planets, with evolution to take drastic changes on a water-world Earth, and a small, Mars sized Theia. Yes, in this world, there are two planets with life in this solar system. Infact, chance has had the evolution of the basic essentials of the life from our won earth in these lifeforms as well.