Oh wow, this takes me back to my days of hunting down obscure fantasy novels! There's this one series called 'The Demon Accords' by John Conroe that kinda fits—though the succubus isn't the main protagonist, she's a major player. The books blend urban fantasy with a dash of romance, and the succubus character, Tanya, is way more complex than your typical seductress trope. She’s got layers, like an onion wrapped in leather and shadows. Then there’s 'Succubus Blues' by Richelle Mead, which flips the script by making the succubus the lead. It’s part of the 'Georgina Kincaid' series, and Georgina’s struggles with her nature and morality are weirdly relatable. Mead’s writing makes you root for her even when she’s toeing the line between chaos and redemption.
If you’re into lighter tones, 'How to Survive as a Villain' (a web novel) has a succubus-ish antagonist who steals the show. It’s more comedy than dark fantasy, but the character’s charm is undeniable. For something grittier, 'The Succubus' by Daniel S. Fletcher dives into horror—think psychological twists and body horror. It’s not for the faint of heart, but if you want a protagonist who’s equal parts terrifying and tragic, this one lingers like a fever dream.