He could turn into a more cynical character. After betraying God, he may start to view the world in a more negative light. He might believe that there are no truly good or right paths, since he's strayed so far from what was considered the ultimate good (God). This could lead him to be less trusting of others and more self - centered in his actions.
Percy would likely become a more conflicted character. He'd constantly be second - guessing his actions. On one hand, he might feel that he did what was necessary, but on the other, he'd be haunted by the knowledge that he betrayed a powerful and benevolent being. This internal struggle could make him more withdrawn and brooding.
His relationships with others could be severely affected. His friends might start to question his loyalty, and he would have to work hard to regain their trust. He may also develop a new sense of empathy towards those who have been betrayed, trying to make up for his own misdeed.
He would likely become more assertive. As a god, he has more power and responsibility, so he can't be as laid - back as he was before. He might also develop a more primal side, influenced by the wolf nature, like being more instinctive in his decision - making.
Another plotline might be that Percy betrays God out of a sense of self - preservation. Suppose there's a great threat coming, and Percy believes that siding with an enemy of God is the only way to save himself or the world he cares about. He might think that God's power is not enough to protect them, and so he makes a deal with the other side, which is seen as a betrayal.
His character might become more aloof. As a primordial god, he would be far removed from the normal world of demigods. He'd likely have a different perspective on things like friendship and loyalty. For example, he might not be as quick to jump into a fight for his friends as he used to be, because his new status would bring a different set of responsibilities.
If Percy Jackson becomes a god in a crossover fanfiction, his character would experience a significant transformation. He has always been a hero who fought for the underdog. But as a god, he might have to make difficult decisions that could go against his old principles. His view of right and wrong could become more nuanced. He would also have to deal with the envy and fear of those around him. His mortality - which was a big part of his identity - would be gone, and he'd have to redefine himself in the context of immortality. His sense of time would change, and he might start seeing things from a much longer - term perspective. All these changes would make his character much more complex and different from the Percy we knew as a demigod.
He would probably become more empathetic. As the God of Love, he'd need to understand the feelings of others deeply. So, he might be less impulsive and more patient when dealing with people.
He might become more solemn. As a god, he has more responsibilities. So, he can't be as carefree as he was as a demigod. He would need to think about the big picture all the time.
His personality would likely experience a shift towards a more solemn and responsible demeanor. With godly powers come great responsibilities. Percy would no longer be able to act as carelessly as he did as a demigod. He might become more reserved in showing his emotions, especially as he realizes that his actions as a god can have far - reaching consequences. Also, his loyalty might be tested as he has to balance his new divine status with his relationships from his mortal days.
He might face immediate retaliation from Chaos's forces. They could be extremely powerful and Percy would have to fight for his life.
He'd probably be more morally strict. In the original Percy Jackson stories, he has a more fluid sense of right and wrong based on Greek mythology. But if he were the son of the Christian God, he'd likely adhere more to the Ten Commandments type of moral code. For example, he might be less likely to use deception in his battles.