The obvious antagonist could be the Titan of Earth itself. Since it's a powerful being, it could be causing chaos and destruction as it tries to regain its former power and influence. Its very existence might be a threat to the balance of the world that Percy and his friends are trying to protect.
" Celebrating Years " was a story that happened after the destruction of Earth. After the large-scale war led to the destruction of mankind, human civilization degenerated and was rebuilt, entering the era of feudal empires. The story was set in a distant future era where nuclear war had occurred, and the Earth had fallen into an environment of nuclear radiation. The surviving humans degenerated into primitive humans and gradually evolved into physiques that could coexist with nuclear radiation. In this world, humans had already lost the science and technology of the past. They could only go through the process of primitive evolution again. The story took place in the next era of Earth. The human civilization of the previous era was destroyed by a nuclear war. The surviving humans mutated under the effects of nuclear radiation and evolved the ability to use nuclear radiation to strengthen their body functions. In this world, humans had already evolved to the stage of ancient dynasties, and nuclear radiation energy was also known as true qi by martial artists. In short," Celebrating Years " took place in the future after the destruction of the Earth, depicting the story of the degeneration and reconstruction of human civilization.
I'm not entirely sure specifically what the 'After Earth' novel is about as there could be many interpretations. However, generally in a story with such a title, it may deal with the consequences of some major catastrophe on Earth. This could mean the breakdown of civilization, the emergence of new threats, and the journey of the main characters to either find a new place to live or to restore the old world in some way.
It's fiction. 'After Earth' is a science - fiction movie that presents a post - apocalyptic Earth scenario which is not based on current scientific facts but rather on creative imagination for the sake of entertainment.
Perhaps in the fanfiction, the Titan of Earth has a connection to Percy's family heritage that he was unaware of. This discovery leads Percy on a journey to understand his own powers better. He has to face challenges like dealing with the Titan's minions who are trying to use Percy to fully revive their master. Along the way, he also has to balance his normal demigod life and relationships.
Not having read the 'After Earth' novel makes it difficult to name the main characters precisely. But generally, in such a novel, we can expect main characters such as a protagonist who is on a quest. This could be a physical journey to find a new home or a metaphorical journey to discover the truth about what happened to the Earth. There may also be a female character who is as tough as the male characters, perhaps a healer or a strategist, and a group of side characters who support the main character's journey, each with their own backstories and motives.
In the 'After Earth' short story, it could also explore themes like the re - building of society. It might show how people start to form new communities, develop new technologies or ways of living based on the remnants of the old world. It could be about the hope that still exists among the survivors, despite all the hardships they face, and their efforts to create a better future for themselves and the next generations.
In the 'After Earth' original story, the main characters are on a journey of self - discovery as well as survival. The son, who initially seems inexperienced, has to grow up fast. The father, on the other hand, uses his skills and knowledge to guide his son. They are constantly on the move, trying to reach a safer place. There are moments of high tension as they encounter different perils, such as attacks from creatures that have adapted to the new, harsh Earth.