Perhaps a plot where Percy forms an unlikely alliance with some of the more neutral or even hostile creatures in Tartarus. He could use his charm and wits to convince them to help him in his struggle against the greater evils of that place. In this way, he learns more about the complex hierarchy and politics within Tartarus.
One possible consequence could be that he becomes even more powerful in a dark way. Tartarus is full of dangerous and ancient forces. Staying there might expose him to unique and powerful magics that change him. For example, he could gain new combat skills or the ability to control certain Tartarus - born entities.
Another character that could be involved is Nico di Angelo. Since he has some experience with the Underworld and Tartarus, he might try to find a way to communicate with Percy or even attempt a rescue mission. His powers and knowledge would play an important role in any interaction with Percy in Tartarus.
It's also possible that there could be a new, unknown force in Tartarus that has been awakened by Percy's presence. This new entity could be extremely powerful and oppose Percy at every turn. It might be some sort of ancient, primordial being that has its own motives for not wanting Percy to succeed in whatever his mission in Tartarus is.
One possible plot development could be Percy facing off against new and terrifying monsters that are unique to Tartarus. Maybe he discovers some long - lost secrets about the place that could change the way the demigods view Tartarus in general.
There's no way to tell who the author is just from the title 'percy is tartarus fanfiction'. It could be written by any fan of the Percy Jackson series who wanted to explore this particular scenario in their own writing. It might be someone new to fanfiction writing or an experienced writer in the Percy Jackson fan community.
Well, it could be about Percy's experiences in Tartarus. Maybe it's a fictional account of Percy facing the extreme challenges and horrors that Tartarus has to offer. It could involve his battles, his relationships with other characters while in that hellish place, and how he overcomes the difficulties there.
Well, it could be about Percy, perhaps from the Percy Jackson series, staying on Ogygia. Maybe it explores his experiences on that island, like his interactions with the nymph Calypso who lives there. It might also touch on how he copes with being stranded or what new things he discovers about himself and the place.
Perhaps he could make an alliance with some of the less hostile creatures in Tartarus. There might be beings who are also tired of the chaos and want to help Percy in exchange for something, like a promise to free them from Tartarus if he ever gets the chance. Percy is known for his charisma and ability to make friends, even in the most unlikely situations.
Annabeth could be a likely candidate. She's always been by Percy's side, and she'd stop at nothing to save him. Her intelligence and combat skills would be useful in the dangerous environment of Tartarus.