There could be some minor gods or spirits that have been trapped in Tartarus but are still benevolent. These could be beings that Percy and Annabeth come across and who decide to help them in their journey. For example, a spirit that has knowledge of the layout of Tartarus could guide them away from the most dangerous areas. Another possibility is some half - forgotten heroes who have been in Tartarus for a long time and have developed unique skills to survive, and they join forces with Percy and Annabeth.
Annabeth is a very likely ally. Their relationship is so strong that she would follow him into Tartarus and be by his side through thick and thin. Grover could also be an ally. He's Percy's long - time friend and his skills as a satyr could come in handy in Tartarus. Nico di Angelo is another possibility. His knowledge of the Underworld and his powers over the dead could be useful in the dangerous Tartarus environment.
There might also be a lost spirit or a demigod who was previously trapped in Tartarus and has managed to survive. This character could share their experiences and skills with Percy, and together they could try to find a way out or at least make the best of their situation in Tartarus.
In this fanfic, they might face terrifying monsters. Tartarus is full of dangerous creatures, so they could be constantly fighting for their lives, like battling against ancient Titans or monstrous beasts that are native to that hellish place.
He could find some minor gods or goddesses who have been banished to Tartarus. They might see Percy as a way to get revenge on the Olympians or simply a means to escape. Another potential ally could be some of the more intelligent monsters, like a centaur who has been there for a long time and has knowledge of the place.
Bob the Titan could potentially be an ally. Since he has some knowledge of Tartarus and has shown kindness before, he might come to Percy's aid again. He could help Percy navigate the dangerous areas and avoid some of the more powerful threats in Tartarus.
Grover could also be an ally. His connection to nature might give Percy some unique advantages in Tartarus. Additionally, some of the less hostile creatures in Tartarus, like the friendly Cyclopes, could side with Percy. They might see him as a more just ruler compared to the chaos that usually reigns in Tartarus. Also, Chiron, with his vast knowledge and experience, could offer guidance from afar, which could be considered a form of alliance.
As for enemies, Percy could encounter the Titans who were once banished there. They might see Percy as an intruder and a threat, and try to eliminate him. Also, the monstrous creatures that lurk in Tartarus, like the Empousai or the Chimera, could be his foes.
In this fanfic, Percy could develop a darker side. The horrors of Tartarus might make him more ruthless when it comes to protecting himself and Annabeth. Annabeth, on the other hand, may become more empathetic. She could see the pain and suffering of the other beings trapped in Tartarus and try to help them, which would shape her character in a new way. Also, their relationship would develop further. They would have to trust each other completely, and this could lead to a more mature and deep connection between them.
In some fanfictions, a possible plot development is that Percy and Annabeth discover a long - lost secret or power within Tartarus. This could be something that gives them an edge in their fight to escape or a knowledge that changes their perspective on the whole Greek mythology world. As they explore Tartarus, they may find ancient artifacts or meet forgotten gods who have been trapped there for ages. These encounters can lead to unexpected alliances and revelations that add depth to the story.
In some fanfictions, Annabeth and Percy might struggle with PTSD. They could have nightmares about their time in Tartarus. Percy might be overly protective of Annabeth, and they may need time to heal their emotional wounds together.