One consequence could be Percy becoming an outcast among his fellow demigods. Since his powers now come from Kronos, they might see him as a threat or a corrupted being.
It could be that Kronos believes Percy has some hidden potential that, when combined with his powers, would lead to a situation beneficial for Kronos. For example, Percy's strong connection to the sea could be used in a way that disrupts Poseidon's domain and the balance among the gods. Kronos, being the Titan of time and a master of long - term planning, might foresee a complex chain of events that would unfold if Percy had his powers.
On a personal level, Percy might have to deal with the emotional toll of killing Kronos. It could be a very traumatic experience for him, even if Kronos was an enemy. He might have nightmares or second - guess his actions. Also, his relationships with other characters might change. Some might fear his new - found power, while others might be more drawn to him because of his victory.
He might lose control of his abilities. For example, if his power is related to water, he could cause unexpected floods that harm innocent people or damage the surrounding environment.
One possible consequence is that the demigod world would be thrown into disarray. Percy has been a key figure in maintaining some sort of order, and with Kronos in control, that order would be shattered. Another consequence could be that the Gods would be in a real bind. They already had trouble with Kronos before, and now with him in Percy's body, it would be much harder to fight him.
Well, one possible consequence could be that Percy gains an immense amount of power. Kronos was a very powerful Titan, so Percy might become nearly invincible. He could also face some internal struggles as Kronos' essence might try to influence his mind and actions.
In a fanfiction where Percy gains all of Kronos' powers, he would likely become extremely powerful. He could have control over time, which is one of Kronos' major abilities. This might lead to him being able to manipulate events in ways no one else could. For example, he could go back in time to prevent disasters or change the outcome of battles.
She could potentially have the power of regeneration. Kronos was a powerful being, and if she inherits some of that essence, she might be able to heal from wounds faster than normal demigods. This would make her a very tough opponent in combat as she could keep coming back even after taking serious hits.
His powers would likely be a blend of Kronos' and Rhea's. Kronos was associated with time, so Percy might have some control over time. He could slow it down or speed it up in a small area. Rhea was a mother goddess, so Percy might have a strong connection to nature and the ability to heal. This is different from his original powers as Poseidon's son where he mainly had control over water and could communicate with sea creatures.
It's possible that his powers could even be enhanced in some ways. Losing an eye could make him more in tune with his other senses, and this could translate to his powers. For instance, his ability to sense danger through water vibrations could become sharper as he has to rely more on it. His powers might also develop in new directions. Maybe he could start to use water to create illusions to compensate for his lost vision in battle, like using water to project false images of himself to confuse his enemies.
In many fanfictions, Percy might use his water powers in a unique way. Maybe he combines his control over water with his sword fighting skills. He could create a giant water vortex to disorient Kronos and then strike with Riptide while Kronos is off - balance.