This is a new OC I've been brainstorming for nearly a year. I hope to one day do something serious with him (like a comic or even a game).

Onox was 'created' by Malitus as an experiment both to revive the then extinct Dark/Black/Onyx Dragonflight and to create the 'ultimate' dragon lifeform for Malitus to possess. Malitus wanted to hijack the body of a pantheon (or anything close enough in might) and become strong enough to cast the 'elderspell' to absorb all forms of energy (life, mana, etc) into himself -- ultimately becoming truly omnipotent.

Onox had it rough from day one. His parents were forcibly made to conceive his brood, and their eggs were then taken and infused with dragon quintessence in a deadly experiment. Only Onox's egg survived the infusion, and it gave him his ability to assume other dragon forms, the ability to use all the breath attacks of the other elements, and ultimately giving him physical traits of other dragons as a side-effect. His mother died shortly after as a result of being forced to lay so many eggs, his father went insane due to mind control, and worse Malitus used this to his advantage; he immediately manipulated Onox's father into thinking mortals forced them to mate and killed his mate afterwards to spite him, which led to Onox's father starting a war with them (and resulted in his own death), and then used that war to start manipulating Onox overtime.

Onox is a dark dragon and thus is feared by the world (since his dragonflight once tried to wipe everyone out and his brood were driven to extinction for it). As such, Onox ultimately wants only to be accepted and part of the world who hates and fears him even though he initially had no ill will towards it.

Malitus eventually manipulates Onox into hating the world and allows Malitus to possess him symbiotically for the power needed to obtain all he desires (vengeance and a kingdom that loves him), Onox encounters hero, who in a twist -- befriends Onox, but as time goes on Malitus eventually starts becoming strong enough to control Onox as well. Then the usual dark warlord/evil possession tropes happen and hero is forced to kill him. Unfortunately, Malitus was counting on this, and gains full possession of Onox's broken and dying body. End of the World happens as Malitus uses Onox's body.

Then Past!Hero gains Future!Hero's memories and sets out to find Onox's egg to befriend him again and destroy Past!Malitus, Future!Malitus notices after hero accomplishes both, and timetravels back to possess Onox himself and preserve the timeline... Story arc 2 starts from here.

Onox's main shticks is being able to turn into any type of dragon (even ones completely foreign to the setting), gaining their traits and abilities while in that form.

He also is a powerful warlock+warlord combo who has strong dark elemental magics (Think Exdeath or Golbez), curses, and other types of dark arts. He can turn mortals into Kobolds or even a Dragonborn if the mortal is exceptionally strong.

Onox is very prideful and appears aloof at times, and can sometimes be a bit childish and stubborn. He is also a bit short-tempered, though he usually brushes it off right away (However, he might secretly curse his offender for a week or two), but he is truly terrifying when actually provoked into violence.

On the otherside of the coin, Onox genuinely enjoys the company of others, especially friends and ESPECIALLY family, and will 100% back up his bluster when push comes to shove for their sakes. He also loves mortal life; often comparing it to fireworks (which he loves). That said, he does tend to keep them at arm's length (he's fully aware of their prejudices and vices, especially towards others outside their own kin).

Still piecing this all together, but so far everyone has loved it. He was largely inspired by Fire Emblem Awakening (big bad possesses major NPC and destroys world; forcing heroes to time travel to fix it), Housamo's Chernobog (dark overlord who is forced into the role in-spite of wanting nothing to do with it), Bowser (affable, hotblooded king who wants to has well intended desires and ambitions, but does it all the wrong ways) and several concepts from WoW (a few lore concepts from the black dragonflight, Wrathion, and the BWL raid).