The Shadowfell's God

Shadows

The Shadowfell was born in the time of the Archlords. It began as little more than a corner of the Astral Plane, where dreams give rise to life. Alenta, the most human of the Archlords, claimed this corner of it for himself. He would use it to enjoy his privilege as a creator god, and to deny its use from his fellows. Most of them would use it for nothing but ill.

...but he found that he could not use it. Alenta was by far the least interested in this pantheon with the business of creation, but here when he put an effort forth nothing happened. The plane writhed, contorted to avoid his attempts to create a mental progeny. It rejected him, and stayed barren. Frustrated, Alenta warded the place off from the other Archlords and abandoned it for more hopeful pursuits.

When he left it unchecked, it began to fester.

Alenta's folly was that he attempted to create life through magic. He tried a physical creation of life - to craft flesh and bone into a recognizable form. The Astral Plane does not play by such rules. It is the kingdom of dreams. The tangible has no power there. But still, residue from his efforts eventually manifested as a race known as Shadar'kai.

Another side effect of Alenta's attempts at creation were a distortion of this section of the Astral Plane's metaphysical methods. The will of an Archlord is not so easily resisted, and the plane had to change itself to overcome Alenta's primal magic. So, this section of the plane broke itself off. Going even further, it took on a niche. It would not create life from just any dreams. Exposure to Alenta's blackened machinations meant it would only accept nightmares as fuel for creation.

Millennium passed. Mortal night terrors birthed a menagerie of horrors within the Shadowfell, and where they could Shadar'kai built up their civilizations. This relationship was... unsustainable. Eventually the Shadar'kai learned of their origin, and called upon their creator god. Alenta, surprised that the territory he'd neglected had grown fruit, discovered the beasts on the plane and quickly plunged it into a civil war.

Blows were exchanged. The Shadar'kai, reunited with their god, fought against the rest of their world. Legions were slaughtered and rebuilt in days on both sides. The stalemate calcified, until the civil war was nothing more than worthless bodies being thrown at each other.

This is when the Egg hatched.

Madness

The Shadowfell has a habit of recreating locations on the Material Plane imperfectly. One such location was the Divine Womb, the birthplace of Loom's gods. The mechanics of that place are outside of the scope of this post, but thankfully the Shadowfell's distorted mirror of it function in very simple terms.

Instead of a Womb, the Shadowfell had a Divine Egg. A singular, massive embryo, holding an incubating god. Whereas Loom's gods were born from mortal hope, the Shadowfell would only release its god when the plane was completely hopeless.

Divine Wombs will give birth to a Lastborn God at the end of their planet's lifespan, but the Shadowfell contained only a Firstborn God. As opposed to being the synthesis of its planet's history, the Firstborn God would exemplify everything the Shadowfell isn't. And it would bear the visage of its greatest criminal.

The Shadowfell was a place of madness and shadows. Alenta had rendered it such when he tampered with forces he didn't understand, and then returned only to plunge it into hopeless war. And so the Divine Egg finally cracked open, giving birth to his only son: Alentyan, the god of Light and Wisdom.

Peter Mohrbacher

After this event, Alenta's interest in the civil war dwindled. He departed the Shadowfell in disgrace, and his people followed suit. They went to Vessel, one of Loom's three moons.

Alentyan left as soon as he was born. He had no purpose here. Its denizens cared not for either of his disciplines. The Material Plane was much more accommodating, and that is where he resided for thousands of years. He was a sage for those who sought him out, bringing illumination to those he deemed worthy. He lacked interest in the position of "god," but when a council of others like him sought to care for the planet in its darkest hour he found no good reason to exclude himself, and took his place among the Thirteen.

The Shadowfell stayed as it had been after Alenta left. A small group of belligerent Shadar'kai remained to continue fighting against the beasts they could take on. It produced the finest monster hunters in the planescape for generations to come. 

Dreams cannot be tamed, even by the divine. Light and wisdom will always flee from a place of shadows and madness.