Well, Percy in the 'God of Assassins' fanfiction usually develops a darker side. He has to face harsher situations and make tougher decisions. His loyalty is also tested more severely. He might have to choose between his friends and his newfound assassin duties. This makes him grow in a different way than in the original series. He also becomes more secretive as he has to hide his assassin - related activities from those he loves. And his view of the world changes as he sees the underbelly of the godly and mortal worlds through the lens of an assassin.
In these fanfictions, Percy's character is often more edgy. He has to be more calculating and less impulsive compared to his original self. Since he's dealing with the assassin - like role, he can't just rush into things. For example, he might take more time to plan his attacks against enemies.
As a baby, Percy's character development would start from a very innocent and instinct - driven state. Instead of the typical teenage bravado, his early development could focus on his natural abilities emerging in a more uncontrolled way. For example, he might accidentally zap things with his water powers when he's excited or scared.
Percy could start to form new relationships within the Faunus community. These relationships could teach him different values and ways of life. Maybe he'd meet a Faunus mentor who would help him understand and control his new Faunus powers, if he has them. This would be a big part of his development, as he'd be learning from a completely different perspective than he's used to at Camp Half - Blood.
Their relationship could be developed by having Percy's father teach him new and advanced powers related to the sea. This would create a more mentor - student dynamic.
Percy would likely be more in tune with the concept of home and family. Since Hestia represents the hearth, Percy might be more nurturing and protective. He could develop a stronger sense of responsibility for the well - being of his friends as if they were his family.
Percy would likely be more brooding. Since Iapetus was often seen as a rather serious figure in mythology, Percy might inherit some of that solemnity. He could be more withdrawn, thinking deeply about his new identity.
In 'Percy Jackson General of Kronos' fanfiction, Percy's character can be developed through his journey of self - discovery. He's in a new and complex role. He could start to explore his own power limits in this new position. Maybe he discovers new abilities that come with being the General. He also has to deal with the reputation of Kronos. Is he going to let that taint his own reputation or is he going to redefine what it means to be the General? His decisions in these areas will greatly develop his character as he tries to find his place in this new and dangerous world.
She could be more in tune with her femininity, using it as a strength rather than a hindrance. For example, she might be more perceptive about emotions, both her own and others', which could help her in diplomatic situations with the gods. Instead of the more straightforward and sometimes brash approach of the original Percy, Fem Percy could be more subtle and strategic.
One way to portray Percy's family differently in fanfiction is to give them more power. For example, Sally could be a powerful seer like Rachel. This would change how Percy interacts with his mom as she could foresee some of his future battles and give him advice based on her visions. Another way is to make Paul more of a fighter. He could have some hidden combat skills and help Percy in his battles against monsters.
Percy could be developed by facing moral dilemmas. For example, when dealing with the eldest Titan, he has to decide whether to trust this ancient and powerful being. This forces him to grow and think more deeply about right and wrong.
Developing his powers further is also a way. Since he's the son of Nyx, he could learn to manipulate different aspects of darkness like creating illusions using shadows or traveling through the dark realms faster. This would not only make him more powerful but also show his growth as a character as he masters these new abilities.