Neverborn.
You are a Demon, a metaphysical being formed of the congealed essence of mortal vice, greed, and blasphemy. Your kind are made of and feed upon evil emotion, and while vanishingly rare, are distressingly common when one considers the scale of atrocity it takes to bring one to being. Demons are the first and foremost denizens of the thousand hells, a nigh-infinite labyrinth twisting between worlds, and the ephemeral nature of each is anathema to reality, draining the very foundation of all that is decent and holy wherever they are found.
Most Demons are weak, and subservient to the whims and will of another, an Arch-Demon whose strength is such they are able to manifest their will over an entire layer of the thousand hells. The Arch-Demons eternally feud for dominion in a diabolical fray, and condemn mortal souls to torment to sustain themselves and fuel their efforts. You are a new Arch-Demon, manifested wholesale from a pocket of malice, you slew the former ruler of your layer, and claimed iron-fisted rule over what remained with their passing.
No matter the scale of their malignant debauchery and crooked corruption, each Demon has a full name which is an innate part of them. When it is spoken or written, no matter the place or circumstance, they are instantly aware and given the briefest moment to exert their will upon creation. Each Demon also has a True Name, which is not known to them, and the slightest mention of which forces obedience to anyone and anything which dares utter it.
Though your True Name is not known to you, you are nonetheless able to determine your colloquial designation. What is your name?
Each Demon has a hideously powerful True Form, the very sickening sight of which sends all but the holiest and bravest of men to the deepest depths of dreadful despair.
Upon your inception your being was yet malleable and you found yourself willing and able to shift your impossible physicality to suit your unholy desires. What is your True Form?
Lastly, while each Demon is well-versed in every form of wicked perversion of all that is right and good, each has a favorite blasphemy, one that is near and dear to their blackened hearts, which they wield with fearsome potency.
Of the stereotypical seven deadly sins, which do you most revel in, and wield with the highest proficiency? Your True Form should be taken into account when coming to a final decision, unless you're one of those which glories in deception and misdirection.