I’ll keep this simple. Actual villainy and an ending that doesn’t force me to work together with the heroes to fight off some bigger threat. Excuse me, but I am the biggest threat in this story, not some recently awakened ancient evil, not some kind of evil entity that comes from outer space, and definitely not something which comes from another dimension, no, it’s me. Is it too much to ask to make us the final boss? Must you make me work together with the heroes?
Now, for details.
I want to have ties with my minions (or comrades if we’re the one working for the overlords), I don’t want them ignored in favor of giving more screen time for the heroes and me, no, I want to build close ties with them so that when the time comes for me to sacrifice them or when they eventually defect to the heroes side, the emotional impact would be that much greater.
I don’t want a redemption arc, take backs are for loser. But I do want a detailed start of darkness, preferably one that span years or decades, not just some ‘here’s a very traumatic event for your MC, bam, they are now dead set on becoming a villain for *insert whatever reason here*’.
No, I want it to be a constant suffering or humiliation, not just a single horrific event. Because if all it takes is one bad day to reduce the sanest man alive to lunacy, chances are all it takes is one good day to snap them out of it.
I want them to become progressively embittered by it. I want to see their optimism and ability to trust to slowly leave them. I want to see them moving from cursing their luck to cursing their life, then cursing their existence to finally cursing the world.
I want to see the embers of anger, hate and sadness inside their heart slowly turns into a burning inferno. I want to see their despair, their desperate attempt to hold on to the vestiges of their positivity, their trust, kindness, happiness, restrain as it leaves them each day, to see them utterly broken and feebly clutching onto whatever positive point they have left, and to see the moment when they finally snap as all that left is malice.
Now, for an even more *gruesome* details
I want to see the world slowly falls into chaos, as panic and hysteria washes over the land.
I want to see that moment where we finally crossed the moral event horizon, and is now irredeemably evil. To see the heroes look upon us with horror and fear etched onto their faces. To see their despair as their attempt ultimately amounts to nothing.
I want to torment the heroes both physically and mentally. To hear their scream of pain as I do whatever I pleases with them, to hear them begging for me to stop with tears streaming down their face. To hear their anguished wail as they see their loved ones is broken and ‘corrupted’. And to laugh with mad glee at their despair.
I want to hold their loved ones hostage and use them to force the heroes to do my bidding, and kill them when the heroes are preoccupied with the task. To smile in sadistic pleasure as I respond to their “But you promised!” with a simple “I lied.”.
I want to see all my machinations and plans comes together beautifully, and let out a contented sigh as I know that the heroes are practically powerless to stop it.
I want to frame the heroes as the bad guys and gain myself public adoration. To see the common folks throw trash at the heroes. To see the common folks worshipping me and look upon me with hope and trust in their eyes. To be heralded as a hero by the public while they condemn the heroes as the villain, delicious irony.
I want to pull a Griffith.
Finally, for the simple details (it's oxymoronic, I know)
I want to have one of the heroes as an RO, yes, it’s counterintuitive to my previous points, but such is the duality of the nature of man.
I want awesome character design.
I want to create powerful weapon.
I want to wield dark magics, preferably forbidden ones.
I want to take a vacation every now and then.
I want to build doomsday devices, plural, just because I can.
I want to create monsters that defies reality and logic.
I want to have a child and make them my apprentice.