One common theme could be power and its consequences. Since Percy is an elder god, he has a great deal of power, and the fanfiction might explore how he uses or misuses it.
I'm not sure specifically which 'Percy is one of the elder goda fanfiction' works are good. You could try searching on fanfiction platforms like Archive of Our Own. They usually have a wide range of works and user reviews to help you find interesting ones.
The novel leveling style and the mortal style were two common fantasy novels. There were some differences between them.
Leveling up meant that the protagonist would constantly grow and improve his abilities through combat, cultivation, and other methods to continuously improve his level and ability, and finally defeat the strong enemy to become a powerful leader. The main characters in leveling-up novels would usually experience many difficult challenges and tests to continuously improve their combat skills and abilities, and eventually become powerful main characters.
The Mortal Style referred to the main character absorbing natural elements during the process of cultivation to improve his ability and finally reach an extraordinary realm. The protagonists in mortal novels usually had unique abilities such as absorbing natural elements, manipulating wind, water, fire, and other elements. They often interacted with mysterious existences and sometimes experienced the test of humanity.
The main difference between the leveling style and the mortal style was the protagonist's ability and growth process. The protagonist of the upgrade path would usually continue to grow and eventually become a powerful leader. The protagonist of the mortal path had a unique ability and growth path. The growth process was even more magical and mysterious.
In leveling light novels, the leveling system often involves gaining experience points (XP). Characters usually get XP by defeating enemies or completing quests. For example, in 'Sword Art Online', players earn XP through combat in the virtual world. As they accumulate enough XP, they level up, which usually means an increase in stats like strength, agility, and intelligence.
Sure is! Solo Leveling is a well-known manhwa that has captured the attention of many readers. It features exciting action and interesting character development.
Monster-fighting novels usually described the protagonist in a dangerous and challenging adventure world. Through constant fighting and improving his strength, he gradually grew into a powerful warrior or assassin.
In novels, the protagonist would usually go through a series of missions and challenges, in which he would encounter various monsters and enemies. These monsters were usually constantly upgrading and evolving to have greater strength and abilities. The protagonist needed to constantly fight and overcome these challenges in order to finally defeat powerful enemies and obtain higher levels and abilities.
In novels, the main character would often make friends with other characters and take risks with them. These characters usually had their own unique abilities and stories. They would fight and level up with the protagonist to face the various challenges of the world together.
Fictions about fighting monsters and leveling up tended to have positive and uplifting topics that encouraged readers to realize their dreams and goals through continuous efforts and struggles, to become a powerful character, and to show their strength and value in the adventure world.