I've read most of Simone Elise's stuff over the last few years, and honestly, the obsession with powerful, secret identity leads is basically her brand.
It's not just about werewolf alphas or vampire kings, though there's plenty of that. It's this specific dynamic where the main character, usually a woman, has this incredible hidden power or lineage that she's either forced to hide or is actively suppressing because of trauma. The tension comes from the slow-burn reveal to her fated mate, who's often the head of some supernatural faction, and the subsequent power shift it causes in their relationship. The 'rejection' trope gets turned on its head a lot.
Beyond that, there's a strong thread of found family. The protagonists are frequently isolated or betrayed by their blood relatives, so they build this fierce, protective circle of friends or pack members who become their real home. The romance is intense and possessive, sure, but the loyalty to that chosen family is just as important. I think that's why her books resonate; it's escapism into a world where you're not just loved, you're fiercely claimed and protected.