One idea could be that Percy, as the lone warrior, has to face a new threat alone. Maybe a powerful and ancient monster that has been awakened and no one else believes in its existence at first. He has to rely on his own skills and the limited resources he has.
The plot might involve the forbidden warrior having some special powers or abilities that Percy has to figure out how to work with. It could be that the warrior was once banished or exiled for reasons that are gradually revealed. And Percy, being Percy, gets dragged into the whole situation, and they embark on a journey full of challenges and self - discovery. Along the way, they might encounter other mythical creatures and have to use their combined skills to overcome obstacles.
In Percy Jackson fanfiction, a perfect warrior often has a combination of physical and mental strengths. Physically, they might possess great combat skills like being proficient in sword fighting, which is a common trait among demigods in the Percy Jackson universe. Mentally, they need to be able to think quickly in battle situations and make smart decisions. For example, Percy himself is a great fighter not just because he can control water but also because he can strategize on the fly.
Well, he could end up in a situation where all his friends are incapacitated. For example, they are put under a powerful spell. Percy then has to be the lone warrior to fight against a group of evil demigods who are trying to take over Camp Half - Blood. He'd have to use his water - related powers in new and creative ways.
It could be an old demigod from a long - forgotten camp. Maybe someone who was exiled or lost during a great war in the past. For example, a demigod who had the power to control the weather but was shunned because people feared their power.
There's also a fanfic called 'Percy, the Holy Warrior in the Underworld'. In this one, Percy is sent on a mission to the Underworld as a holy warrior. It delves deep into the mythology and has an interesting take on how Percy's new role affects his relationships with the gods. The author does a great job of building tension throughout the story.
One common theme is the discovery of hidden powers. Just like in the original Percy Jackson series where he discovers his demigod powers, in these fanfictions, he often uncovers ancient warrior powers within himself. For example, in many stories, he might find that he has the ability to use ancient weapons in a special way.
Well, it could be about Percy going on a solo quest to find a powerful and lost artifact. Maybe he has to face some new and dangerous monsters all by himself, like a horde of fire - breathing dragons that guard the artifact in a hidden lair.
Obviously, Percy Jackson would be one of the main characters. He's the hero of the original series. And then, there's the forbidden warrior. We don't know much about this character yet, but they are likely to be a powerful and mysterious figure.
Percy himself is of course very popular. His heroic deeds and his journey from a somewhat naive demigod to a powerful warrior are always interesting to explore in fanfiction.