Well, Percy's power is more of a natural, in - born ability as a demigod. The Host of Sobek's power is more of a connection to a divine being. Their powers could interact in a way that Percy provides the raw elemental power of water, and the Host of Sobek provides the divine guidance and shape - giving to that water. So, like, Percy could make a large amount of water appear, and the Host could then transform it into a weapon or a shield using Sobek's influence.
A possible plot could be that there is a prophecy that only Percy and the Host of Sobek can fulfill. It involves finding a lost artifact that has the power to either save or destroy the world. Along the way, they face internal conflicts as their different cultures and beliefs clash, but they learn from each other and grow stronger as a team.
Annabeth could be a great ally. She's smart and resourceful, and she could help Percy figure out the mysteries related to Sobek and his Egyptian connections. Her knowledge of architecture and strategy would be useful in any quests Percy undertakes.
Another option could be a corrupted demigod. Maybe a child of a minor Egyptian god who is jealous of Percy's status as Son of Sobek. This demigod could form an alliance with some dark forces and try to undermine Percy at every turn, creating all sorts of challenges for him.
A plot could involve Percy being sent on a mission to an ancient Egyptian underworld realm by Sobek. There, he meets various Egyptian deities and creatures. He has to use his skills as a demigod and his new powers from Sobek to navigate through the dangerous realm and return to the mortal world with important information for the safety of Camp Half - Blood.
Maybe Percy discovers a hidden power within himself that is related to Sobek. For example, he could gain the ability to control water in a more primal and fierce way, like Sobek does. He then has to learn to control this new power while facing off against an enemy who wants to use it for evil. This could lead to some intense battles and character growth for Percy.
The Titans could still be a major threat. Since Percy is now the Host of Chaos, they might see him as a new opportunity to regain power. Kronos could try to manipulate Percy's chaotic powers for his own gain, or maybe use Percy's new status to cause more chaos in the world and then step in to 'restore order' in a way that benefits the Titans.
One great example could be a fanfiction where Percy has to face off against the host of Kronos in a more psychological battle rather than just a physical one. It could explore his inner turmoil as he grapples with the power of Kronos. Another might involve Percy teaming up with some unexpected allies to take on the host, adding an interesting twist to the story.
The contrast between Percy and the host of Kronos is a big draw. Percy represents heroism and the fight for good, while the host of Kronos is a symbol of chaos and destruction. Their interactions can be full of tension and drama.
Percy is the main character so he'll be there. Annabeth will probably be by his side as she often is in his adventures. Leo Valdez could also be a character in this fanfiction. His mechanical skills might come in handy if there are any traps or devices related to the Host of Apophis. Piper McLean could be involved too, using her charm - speak to influence certain situations. And Thalia Grace, the daughter of Zeus, could make an appearance. Her leadership skills and her ability to call lightning could be important in the fight against the Host of Apophis.