You read enough paranormal romance and certain ideas about its heroes become impossible to ignore. The good ones keep showing up, book after book, author after author, like the genre figured something out about desire that the rest of fiction is still catching up to.
The Immortal Hero's Power Should Come With Proportional Loss
If the hero has lived for centuries, he's had centuries to lose things. That math is simple and most writers skip it. They give him the centuries of experience, the slow-earned wisdom, and then forget that a thousand years of living means a thousand years of funerals. His power and his loneliness are the same thing. The immortality that makes him dangerous also makes him isolated.
Christine Feehan understood this when she built her Carpathian males. Over their long lives, they lose their ability to see color and feel emotion. The vampire myth inverted: the creature of the night slowly going gray inside. When the heroine arrives, her presence literally restores sensation. In Feehan's world, it's a biological fact about her supernatural species. What makes it work is that the cost is specific rather than general. Centuries of numbness rather than just centuries of being alone. The difference matters. "I've been lonely for a long time" is a character note. "I haven't seen the color blue in four hundred years" is a wound with edges.
The mistake is giving the immortal hero centuries of experience without centuries of damage. Invincibility without cost produces a hero readers can't care about, because caring requires believing someone has something at stake.
The Supernatural Hero's Self-Control Is His Defining Characteristic
The most desired paranormal hero trait is restraint. He could hurt her, take what he wants. The fact that he doesn't, over and over, in situations where it would be easy, is what makes him trustworthy in a specific fictional way.
J.R. Ward built the Black Dagger Brotherhood on this principle. The brothers contain extraordinary violence all the time, but especially around their mates. Wrath, despite being the king and arguably the most dangerous of all of them, is undone by Beth in a way that reads as genuine vulnerability, something that costs him and that he chooses anyway. The restraint has a price, and readers feel it.
The failure mode is the dangerous hero who reveals himself to be quite harmless the moment the heroine is near. Readers experience this as bait-and-switch. The danger has to stay real or the restraint means nothing. You can't earn credit for holding back a force that was never going to arrive in the first place.