One big challenge could be competition among other researchers. In the fanfiction world, there could be rival marine biologists who want to be the first to discover something new. Percy might also face environmental threats. Things like pollution ruining the habitats he's studying or climate change affecting the behavior of the marine life he's researching. He'd have to find ways to work around these issues to continue his work.
Percy could face difficulties in getting permission to access certain restricted areas of the ocean. Maybe there are military zones or privately - owned areas that he needs to study. Another challenge could be dealing with the bureaucracy of the scientific community. He might have to jump through a lot of hoops to get his research approved or published. And of course, there's the challenge of working in a harsh and unpredictable environment, where weather conditions can quickly turn dangerous.
He could face difficulties in adapting to the new work environment. If it's a very hierarchical place, he might struggle with the strict chain of command. For instance, if he has an idea but has to go through multiple levels of approval before implementing it. Also, the work might be very different from what he learned at Hogwarts. So he'd have to unlearn some things and learn new techniques quickly.
Well, I'm not sure of the exact titles, but generally in such fanfictions, Percy would be involved in things like coral reef conservation. Maybe in some fanfictions, he teams up with other characters to study the migratory patterns of whales. He could also be researching deep - sea organisms that are yet to be fully understood. You can search on fanfiction platforms using keywords like 'Percy' and'marine biologist' to find relevant works.
In a family with two such powerful demigods, there could be a power struggle within the family itself. Their children might grow up feeling the pressure to live up to their parents' reputations. Moreover, Percy and Annabeth would have to decide how much of the demigod world they expose their kids to at a young age. If they expose too much too soon, it could be overwhelming for the children, but if they wait too long, the kids might be unprepared for the threats that come with being a demigod.
He may face challenges in the magical realm. The magic in the Percy Jackson universe might not interact well with his cyborg parts. For example, if he tries to use his powers while his cybernetic parts are active, there could be some unforeseen consequences. Also, he may be an outcast in both the human world (because he's a demigod) and the demigod world (because he's now a cyborg), which could lead to a lot of emotional and practical difficulties.
Plumbers often face the challenge of working in dirty and cramped spaces. Sewers and small utility closets are common work areas. Also, they have to keep up with new technology and building codes. For instance, new regulations about water conservation may require them to install different types of faucets or toilets, which they need to learn about quickly.
She might face challenges with unruly children. Some kids could be overly energetic or disobedient, like a little boy who refuses to sit still during story time. Bella would have to find creative ways to discipline him without being too harsh.
One challenge could be security. Given Harry's fame, there might be Death Eater remnants or nosy reporters trying to crash the wedding. They'd have to set up strong magical wards around the venue.
Naruto would face quite a few challenges. For one, his growth might be stunted as the team overprotects him. He could also face ridicule from outside the team who might see him as a weakling now. Moreover, he has to deal with the internal team dynamics where Sasuke may not be fully accepting of his new role and Naruto would have to prove himself constantly.
One challenge could be the loyalty to their previous relationships or crushes. Percy had a history with Annabeth, and Piper was involved with Jason. Their friends might not be fully accepting at first, which would create social pressure.
One major challenge would be Artemis's vow of chastity. Since she has sworn to be a maiden goddess, falling in love goes against her very essence. In the fanfiction, this could create a huge internal conflict for her, as well as external pressure from the other gods who uphold her vow.