It is a little known fact that every solar system contains Mars. Not Mars itself, of course. But certain suns seem to possess what we might call a habit of Martianness: In every inhabited system so far identified, there is a red planet, usually near enough to the most populous world if not as closely adjacent as our own twinkling scarlet beacon, with proximate lengths of day and night. Even more curious, these planets are without fail named for war-divinities.
Each red planet owns also two moons, just as ours does. Some of them will suffer life to flourish.