Well, clearly Percy Jackson is one of the main characters. He's a well - known demigod in the Percy Jackson universe. And of course, Lady Styx is another main character in this fanfiction. She has her own powers and influence in the Underworld.
The Titans could still be a major threat. Even if Lady Styx is involved, the Titans might see an opportunity to use the chaos she causes to their advantage. For example, Kronos could try to ally with Lady Styx to regain his power and overthrow the Olympians once again.
Yes, there are quite a few out there. You can start by looking on popular fanfiction websites like Archive of Our Own or FanFiction.net. Just search for 'Percy Jackson and Lady Styx love' and you'll likely find some interesting reads. Some might focus on a more romanticized version of their interactions within the context of the Percy Jackson universe.
Some of the gods might also be important characters. Poseidon, Percy's father, could have an interesting reaction to Percy's new relationship. Hades, as the god of the underworld where Styx is located, might also be involved, either as an ally or an obstacle depending on the direction of the fanfiction.
In this fanfiction, Percy Jackson is the central figure as he controls the Styx. But other important characters could be Grover, his satyr friend. Grover has always been there for Percy and could provide support or comical relief. Also, Nico di Angelo could play a significant role. Given his connection to the underworld, he might have some insights or even a conflict with Percy regarding the control of the Styx.
Well, a plot could involve Percy being lured into Lady Styx's domain by a false prophecy. Once there, he finds out that Lady Styx has a plan to flood the mortal world with the waters of the Styx, which would bring death and destruction. Percy has to find a way to stop her, maybe by finding an ancient artifact hidden in the Underworld that has the power to control the Styx. Along the way, he meets some strange and dangerous creatures that are loyal to Lady Styx.
Perhaps a plot where Lady Styx reveals some long - hidden secrets about Percy's past or his family. This could lead to Percy going on a journey of self - discovery while also dealing with the implications of these secrets in the world of demigods.
Archive of Our Own (AO3) is a great place to start. It has a large collection of fanfictions, and you can easily search for 'Percy Jackson and Lady Styx love' in the search bar. The tagging system there helps you filter out the ones that might not be what you're looking for.
Obviously Percy Jackson himself is a main character as it's about his dip in the Styx. His girlfriend Annabeth Chase would also likely be involved. She's always by his side in tough situations and would be there either to support him before the dip or to help him deal with any after - effects.
It could be an old enemy of Percy who has somehow gained power over the Styx. Maybe a resurrected villain from Percy's past who now wants to use the power of the Styx to take revenge on Percy and the gods. For example, Kronos' remnants could have found a way to manipulate the Styx's energy for their own evil purposes.
In a fanfiction of Percy Jackson dipping in the Styx in Tartarus, it might explore the idea of him getting new powers or a stronger connection to his godly side. For example, his water - controlling abilities could become more refined and he could have a better understanding of the Underworld's waters. Also, he could encounter some long - forgotten spirits or creatures that guard the Styx in Tartarus.