Halaan's Curse
Halaan's Curse, more commonly known by its people as Diran, is a singular planet that is orbited by two moons - Amante and Odio. Elemental planes exist parallel to this world, and minorly influence the nature of The Curse's atmosphere, land, and seas. The existing lineage of rulers are descendants of a greater god turned mortal, Halaan. All have been corrupt until as of recent...or so people think.
High fantasy
The Titan of Chaos, Halaan, decided to try to deceive his brother, Hecho, to make a world that he would soon corrupt. Hecho, knowing of his brother's mischievousness, decided to secretly take part of Halaan's soul while he was asleep and bind it to the new world, named Diran. Halaan, when he tried to cause havoc, was instead pulled towards his fragmented soul and was unable to return to the Outer Palace of Gods. Until he is able to find his fragmented soul pieces, imbued into a select few people, he will be bound to a mortal body. The people with Halaan's Soul Fragment possess chaotic magic that is not easy to control. Over generations, however, the magic has grown weaker than the ancestors, and is thus more easy to control. However, two pure mortals with Halaan's Soul Fragments decided to keep their family pure, and their family - the House of Girani - is now the highest ranking noble house.
Only those with Halaan's Soul Fragment can possess magic. The only other way is for a mortal to be granted magic by a fey, demon, or a higher god. Those who do are usually given minor powers related to their patron.