Ohhh, Tartarus and Nyx as parents for Percy? That's such a cool and rare twist! I love how fanfic writers dive into the darker, more mysterious aspects of the 'Percy Jackson' universe. One fic that really stuck with me is 'Shadows of the Abyss'—Percy isn't just a son of Poseidon here but gets this eerie, powerful heritage from Tartarus and Nyx. The author nails the atmosphere, with Percy struggling between his old lighthearted self and this newfound darkness that keeps pulling him in. The interactions between him and Nico are especially intense, since Nico's already got that Underworld connection. There's also a great slow-burn romance with Annabeth, where she's trying to understand what's happening to him while he's slowly becoming something... other.
Another gem is 'Eclipse of the Gods', where Percy's lineage gives him abilities that even the Olympians fear. The writer explores how Nyx’s influence makes him a master of shadows, while Tartarus fuels this uncontrollable rage. The plot revolves around a prophecy that hints Percy might overthrow Olympus, and the way the gods react to that threat is both terrifying and fascinating. What I adore is how the fic doesn’t just make Percy edgy for the sake of it—there’s real emotional weight as he grapples with loyalty to his friends versus the pull of his primal instincts. The battle scenes are epic, but it’s the quieter moments, like Percy talking to Bob in the Underworld, that hit the hardest.