Perhaps they embark on a quest to make Tartarus a more secure place. They know its terrors all too well and want to prevent any other beings from accidentally or maliciously entering. Along the way, they face new monsters and challenges that test their relationship and their skills.
One possible storyline could be them dealing with PTSD. Percy might have nightmares about the horrors in Tartarus, and Annabeth could struggle with sudden bouts of anxiety in seemingly safe situations. They would have to support each other through these tough times, learning to communicate better about their feelings.
Another idea is that they decide to focus on building a new life for themselves at Camp Half - Blood. They start teaching the younger demigods about their experiences, but not in a way that scares them. Instead, they use their stories to inspire the next generation to be brave and resourceful.
Perhaps they go on a quest to find a way to close the gates of Tartarus permanently. This would involve traveling to different places, facing new monsters, and using their combined knowledge and skills. Along the way, their bond would be tested, and they'd have to rely on each other more than ever, making their relationship even deeper.
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.
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.
One popular type of fanfic could be about Percy and Annabeth's journey through Tartarus. It might focus on their struggles, like how they face the various terrifying monsters there. Maybe they use their unique powers and the bond between them to survive. For example, Percy's control over water could be crucial in crossing some of the dangerous rivers in Tartarus, while Annabeth's wisdom helps them make smart decisions when choosing paths in that dark and chaotic place.
One possible plot could be that Annabeth and Percy are in Tartarus. They face numerous challenges while Annabeth is pregnant. Maybe they have to find a way to protect the unborn child from the terrors of Tartarus, like hiding from monsters that are specifically attracted to the new life force. They might also encounter some friendly or at least neutral entities in Tartarus that offer help in exchange for something.
In fanfiction, after Tartarus, Percy and Annabeth could be on a journey of self - discovery together. They've seen the darkest parts of themselves and each other in Tartarus. So they might be exploring who they are now, how they've changed, and how their relationship has evolved as a result. Maybe they take some time away from the chaos of their demigod duties to really understand their feelings for each other.
One possible challenge could be psychological trauma. Tartarus is a terrifying place, and they might have nightmares or sudden panic attacks. Another challenge could be how they are perceived by others. Some might view them as changed or even dangerous now that they've been to such a dark place. Also, they could struggle with readjusting to normal demigod life, like the routine of training and living in the camp, which seems so ordinary compared to what they've endured in Tartarus.
One possible storyline could be their children going on a quest to discover a new hidden part of the demigod world. Maybe they have to find a lost artifact that is crucial for the safety of Camp Half - Blood. Another could be their children facing challenges at school, dealing with both normal school problems and the added pressure of being demigods.
One possible storyline could be that their daughter inherits both of their special abilities. For example, she might have Percy's skill with water and Annabeth's strategic mind. She could go on adventures in the same world as her parents, facing new monsters and challenges. Maybe she discovers a long - lost secret related to the gods that her parents were unaware of.
Percy might become more cautious. After facing the extreme danger in Tartarus, he realizes that his impulsive nature could have more serious consequences. Annabeth, on the other hand, could become more empathetic. She saw Percy at his most vulnerable in Tartarus and now understands the importance of emotional support better.