Sirius Blackdraco

Story: Born in the dark, far reaches of Obsidian Castle, Sirius was whisked away by a goddess at an early age. Said goddess was Kerrytolezia, the one of dreams, lies and tricks. Due to this intervention, the small demon never met his parents. He had grown up in the lilac, nonsense-world of the goddess with floating islands, twisting bridges and nothing but living portals to keep him company. This world was sunken into perpetual dusk, and Sirius didn't see sunlight until about 18 years of age as he was tossed into the mortal realm. It blinded his eyes something fierce, but the demon had to cope. 

There was a distinct feeling that he'd been sent here with some kind of mission. Well, to mop up Kerry's mistakes, that is. The goddess had accidentally spawned an all too ambitious child of supernatural powers that would bring ruin if she wasn't stopped. That happened to be Sirius' goal in the mortal realm. Seek out this girl among humans and get rid of her for good. After some searching, he did in fact find her. She went by "Ravin". Needless to say, still under the influence of Kerrytolezia's upbringing, Sirius hated this girl quite a lot.

He died twice trying to end Ravin's life, something that was nowhere near the goddess' plans. Eventually, she whisked both of them away back to the world of Lunae, one Ravin had never seen. Despite never being there before, she took command of the kingdom known as Challyn and from there, Sirius' quest to kill her continued. Unfortnately, he was thwarted again by the then-fiendish soldiers of Meizha. Sirius' body was tossed off a cliff into a nearby river.
During this absence, Ravin fell into Hell and set course for Obsidian Castle, arriving with a "mission" to kill some kind of eldritch deity. The reigning demon lord, Thaembrion, got fed up with the raving woman and ordered her into exile. However, she disobeyed and woke up one of the mountain-sized Void Fiends that were slumbering in the abyss. It triggered an explosion that wiped half of the fortress city and sent it into the bottomless Void. The demon lord forcefully escorted Ravin out of his province.

Sirius rotted in the river for months before his godly stepmother took pity on him, bringing his body back to life and adorning her "son" with magical glamour to restore his former looks. Sirius was now not much more than a shambling corpse in his essence, as Kerrytolezia stole his soul.
With newfound immortality, he headed for Challyn to finally get rid of the pest that was Ravin. Bribing some of the imperial guards over to his side, Sirius pulled a coup détat and dethroned the woman, turning her into a stone statue before pulverizing the remains.

Inbetween all of this, as preparations, Sirius put an obscene amount of time into studying the arcane arts and rune magic. He quickly became one of the better mages in Lunae, and his magical aptitude rooted from birth helped quite a bit.
Sirius is now the reigning emperor of Challyn, ruling with a fairly benevolent regime even though people are somewhat unsettled by their demonic regent. The Challynese court is known for collections of strange individuals, such as fairies, half-demons and other abominations people dare not speak of.