Good Egg
If you really want to avoid writing a Mary Sue with a very powerful villain, allow him to be blind-sided or surprised on occasion. He's powerful, he can probably get whatever he wants, but his rampages and whims shouldn't be consequence-free.
In fact, looking over what you've got here, I'd think that not thinking things through would be his Achilles heel of sorts. He can do whatever he wants, so why should he sit and make sure that his latest whim can be pulled off without a hitch? It's not like anyone could possibly challenge him or that it could be counter-productive to his overall goal, right? Right?
Time keeps dragging on.
Unchanging Avatar.
I warn you, while this is a great character, this isn't Affably Evil. That implies sophistication, self-control, etc. An Affably Evil villain would only Kick the Dog when they actually need to, not out of anger or spite. Your character seems a little too messed up to qualify.
Except for 4/1/2011. That day lingers in my memory like...metaphor here...I should go.
Yeah, I actually meant Evilly Affable in the thread title. My bad.
I like the suggestion of his weakness being arrogance and an inability to think things through. In fact, I'm already imagining him having some epic Oh, Crap! moments. I think I'm also going to have him suffer from Chronic Backstabbing Disorder to some degree.
The Villain Sue aspect is still a little bit worrying to me. Diablo is probably strong enough to fight his way out of all but the most extreme situations(read: the protagonists at full power and the strongest devas and asuras teaming up on him), and I think he would prefer the Indy Ploy to the Xanatos Gambit(which Diablo wouldn't have the patience to see through any way). I have another issue, however - he is, for all intents and purposes, the biggest Big Bad of the setting, and I want him to play an active role in the plot and be on the front lines of most of the different battles, but the idea of having him almost get beat and running away multiple times seems like it would irritate most readers after maybe the second occurence. I'm thinking about throwing in some Evil Versus Evil to balance this out, how does that sound?
https://soundcloud.com/rich-justice-hinmen Too white for the black kids, too white for the white kids.
I'm working on a character that I think will be really fun to write, but I want to avoid him from taking a hard turn into Villain Sue territory.
Just a brief rundown of the setting - in this Earth, mankind has always possessed magical powers, but has developed along two other races, devas and asuras/demons, who are much, much stronger physically and magically, but technologically and socially more primitive. Gods Need Prayer Badly(for all beings) is in effect, and the MacGuffin is a Cosmic Keystone that gives whoever holds it(currently the deva El possesses it) dominion over the universe, but the responsibility of making sure that no one else takes it.
Anyway, my character, Diablo the Ravager, was a teenaged American mage from Oklahoma who was abducted by hostile demons in an attempt to create a living superweapon. He had a variety of horrendous spells and rituals performed upon him, including several spells that give Diablo power based on human hatred. The end result was a powerful spellcaster who proved uncontrollable. He essentially became one of the most powerful beings around by killing and sacrificing countless lifeforms to himself. He's meant to be the biggest Big Bad around in the scenario, and his ultimate goal is seize the Cosmic Keystone, destroy it, and subject all living beings to an unending nightmare of chaos and torment.
Problem is, I really do not want to write him as a serious villain. He is physically and mentally a 17-year-old boy, and I want him to be humorous in his own evil way, even if he takes to Beyond the Impossible levels. He is definitely dangerous, but he also lapses into Stupid Evil and Chaotic Stupid, and will commit atrocities just For the Evulz(and I do want to have one scene where he literally kicks a dog) He's also a huge geek, as he spent more than 30 years in hiding while recovering his strength and consuming media of all kind, so he is an Otaku and fan of hip-hop.
In terms of personality, I want to write him as Kefka meets [[Eminem Slim Shady]] meets Travis Touchdown. I also plan on contrasting him with a more traditional Lawful Evil demonic villain, and Diablo ends up occasionally being heroic, although without intending to.
Any tips on making sure that I can write him as a humorous Jerkass without hitting Mary Sue territory?
https://soundcloud.com/rich-justice-hinmen Too white for the black kids, too white for the white kids.