To develop the character, start with his backstory. Since he's the son of Kronos, he might have grown up in a very different environment compared to other demigods. Maybe he was hidden away by a minor god who felt sorry for him. His past experiences of being alone and shunned because of his father would shape his personality, making him a bit of a loner at first.
Yes, there are likely fanfictions out there with this concept. Fanfiction writers often explore alternative storylines and relationships. However, it goes against the canon as in the original 'Percy Jackson' series, Percy is the son of Poseidon. But in the world of fanfiction, anything is possible.
Well, Percy's character would go through a major transformation. Initially, he would be shocked and confused about being the son of Kronos and Gaea. This would cause him to reevaluate his relationships with his friends and allies. He may feel isolated as he believes they might not accept him anymore. As he delves deeper into his heritage, he would learn about the history and motives of Kronos and Gaea. This knowledge would give him a different perspective on the world of gods. He would have to make tough decisions, like whether to use the powers associated with his parents for good or evil. Through these experiences, he would become a more self - aware and morally complex character, no longer simply the hero who always follows the Olympians' rules but someone who has to make his own path based on his understanding of his true identity.
In a fanfiction, Percy could face other demigods who are suspicious of him because of his relation to Kronos. He'd have to prove that he's not going to follow in Kronos' evil footsteps. Maybe he teams up with some unlikely allies, like a child of a minor god, to show his loyalty to the good side.
Well, in such a fanfiction, Percy's character arc would be completely transformed. Instead of having the connection to the sea like in the original where he's Poseidon's son, he might have a connection to time or something related to Kronos' powers. His relationships with other characters would also be different. For example, his friendship with Annabeth might be strained as she might see him as a threat due to his new 'parentage'. The story could be filled with internal struggles as Percy tries to come to terms with who he really is and the legacy of Kronos.
Percy would likely become more conflicted. His previous identity as the son of Poseidon shaped his values and actions. But as the son of Kronos and Rhea, he'd have to reevaluate everything. He might become more cautious, as he now represents a more controversial lineage.
Annabeth is often a popular character. In fanfiction, she might play a crucial role in helping Percy deal with his complex identity as the son of Kronos. Grover could also be popular as he's Percy's loyal friend and could be there to support Percy through his struggles related to his new - found heritage.
A great plot could also involve the OC forming an unlikely alliance. He could team up with some of Percy Jackson's friends, like Annabeth. They initially don't trust him, but as they face challenges together, they realize that he's not like his father. This alliance could lead to them facing off against an ancient evil that only the combined knowledge and powers of the OC and the other demigods can defeat.
Well, in a 'Percy Jackson Seventh Son of Kronos' fanfiction, the plot could center around Percy being hunted by both the gods and the Titans. Since he's the seventh son of Kronos, he has a unique power that both sides want to either control or destroy. Percy has to go on a quest to find a way to neutralize this new aspect of his identity so he can live in peace. Along the way, he teams up with some unexpected allies, like a group of demigods who are also outcasts for various reasons.
In these fanfictions, the theme of acceptance is quite common. Percy has to come to terms with being the son of Kronos and Hestia, and the demigod community also has to accept this new reality. Redemption can also be a theme in some cases. If Kronos' dark past is considered, Percy might have to deal with the idea of redeeming his father's name in some way. And of course, adventure is always a theme in the Percy Jackson universe, and these fanfictions are no different. With his new parentage, Percy embarks on new and exciting adventures that are different from the ones in the original books.
One possible plot could be Percy's discovery of his true parentage as the son of Kronos and Rhea. This could lead to a huge power struggle within the demigod world. Other gods and demigods might fear his potential power and try to either eliminate him or recruit him to their side.