In the universe of Blood Sea Song, the most powerful beings, as close to the Actual Creator Gods, For Real This Time, that are known to exist, are Catalysts. Catalysts are entities that live in deep space, physically resembling eel-siphonophore-dragons long enough to wrap around a small star and bite their own tail. Their psychology is utterly alien and inscrutable to humans or equivalents, due to both the sheer magnitude of their mental power, and the very odd pressures imposed by their environment and life-cycle.

Catalysts are mostly solitary, wandering the cosmos according their fleeting whims. They can generate and manipulate absurd volumes of mass-energy effortlessly. The only times they come into contact with each other are to hunt each other and to mate with each other, which is basically the same process. Communication, attack, and the transfer of genetic information all involve shooting beams of light/plasma/exotic particles/coherent gravity waves at each other, just at very slightly different combinations of intensity, composition, and aim. So any of the three could at any moment either secretly be lure for or accidentally become any of the other two.

The only real 'culture' they have is that they create and/or terraform planets and planet-like megastructures as a kind of 'art'. They do this because, in the words of one poet. 'The language of creation is the only language they know. When they laugh, the laugh with rainbow dust-rings around worlds of uniformly tropical climate. When they cry, they cry in landscapes of broken glass beneath ash-darkened skies. Their rage is a ring of volcano-worlds around a bloated red sun. Their madness is clockwork spheres the size of stars built of gears the size of snowflakes; it is an ice-giant marred by a thousand kilometer spire of asphalt and meat; it is a world with a five minute day, and eternal thousand knot winds, where every mountain is hollow and filled with holes, and the land itself screams."

Most worlds are the product of one Catalyst, perhaps remaking it all at once, perhaps grooming and pruning it for centuries or millennia (still an eye-blink in Catalyst lifespans), before judging it complete and moving on. Often a second Catalyst will come along to iterate on a world another created, but only after it has been left fallow for thousands or even millions of years. Some worlds have had dozens of stewards over their billion year history.

The world of Miara is different. It is the only known, surviving instance of a world created by two Catalysts working togeather at the same time. There were two Catalysts. One called (any names are simplified approximations of educated guesses ad infinitum) Devouring Dark, the the other, the Light that Hates. In the space near what would become the planet Miara, they simultaneously attempted to kill and eat each other, but part way through changed their mind, and mated instead. Miara was made into its present state (approximately, this was half a million years ago) in the aftermath, by the two of them working together.

Miara itself is an odd world, but not an especially dramatic one. Its landmasses are lush and verdant, with no deserts to be seen. But the oceans are blood, and strange creatures swim in them. The thick atmosphere makes the tropics cool and the poles warm, but it is so thick that you can not see the stars at night. The night is dead black, when not lit by the moon.

The moon is a dead egg, never to hatch.