How Do Demons Reaction Differ By Personality In Fanfiction Stories?

It really depends on the story's tone. In a crack fic, a demon might just sigh dramatically and ask for a coffee while complaining about the summoner's chalk quality. In a darker horror romance, that same reaction could be a slow, predatory smile that doesn't reach its eyes. Personality filters the supernatural through a very human lens, which is the whole appeal for me. A lazy demon might try to loophole its way out of a contract, while a bored, ancient one might play along just for something to do. The baseline 'demon' stuff is just set dressing; the personality is what makes them a character.

The way writers handle demon reactions always grabs my attention because it can be the whole point of the story or just a background detail. A common trope I see a lot, maybe too much, is the broody, emotionally stunted demon whose personality is just 'angry and possessive'. They snarl, they growl, they destroy furniture when jealous. It's fine shorthand, I guess, but it gets repetitive. I'm way more interested when a demon's personality isn't just a carbon copy of their species lore. Like, I read this one Hannibal fanfic where Will Graham summons a demon that's disturbingly polite and psychologically observant. Its reactions weren't fiery rage, but chillingly calm manipulation, matching Hannibal's own personality projected onto this supernatural entity. That contrast between the expected 'demon' behavior and the actual personality based on the human character it's paired with is where the good stuff hides.

Sometimes the divergence is less about matching a human and more about inverting the trope entirely. A genuinely cheerful, optimistic demon who reacts to holy water with a 'bless you' and finds the concept of eternal torment terribly gauche. Or the anxious, neurotic demon who overthinks every contract clause and has a panic attack when a summoning circle is drawn slightly off-center. Those reactions tell you so much more about the individual character than 'evil monster #3'. I think writers forget that 'demon' is a job title or a species, not a personality. A corporate lawyer demon from the bureaucracy of Hell is going to have a drastically different reaction to a bungled ritual than a feral, battle-scarred war demon from the front lines of some celestial conflict.

My pet peeve, honestly, is when the reaction is totally dictated by the ship dynamic and nothing else. The demon is just a sexy plot device whose personality flips based on whether the author needs them to be dominant or vulnerable in a scene. There's no internal consistency. I'd rather see a demon whose prideful personality leads them to reject a summoning out of spite, even if it means staying trapped, because the idea of being 'ordered' by a mortal is intolerable. That's a reaction rooted in character, not convenience. It makes the eventual connection, if there is one, feel earned.