He might be shocked and a bit disturbed. Percy is a heroic character, and seeing a 'dark' version of himself in fanfiction would be quite jarring. It's like looking into a distorted mirror of his identity.
Percy would probably be confused at first. He has his own self - image and set of values. Dark fanfiction might present him in ways that go against everything he stands for. He could also be a bit curious as to why someone would create such a version of him, but overall, it would be an uncomfortable experience for him.
Most Percy Jackson fans would likely be appalled. The original series is about adventure, friendship, and heroism among kids and young adults. A fanfic with such a inappropriate concept would go against what they love about the series.
He might find it really interesting. Since both Percy Jackson and Carter Kane are from different but equally rich myth - based series, he could gain new perspectives on how to blend modern settings with ancient myths, which is something his own series also does.
He might be amused. Percy has his own set of adventures, but reading about Magnus' would probably make him chuckle at the different takes on Norse mythology in the fanfiction.
Percy could find it both strange and fascinating. Since he has his own set of adventures and challenges, reading about Harry Potter's world through fanfiction might make him think about how different yet similar their situations are. He might be amused by some of the out - of - the - box ideas in the fanfiction.
They might be amused. After all, the fanfiction often portrays them in new and sometimes comical ways. They could find it interesting to see how modern humans imagine their lives and personalities.
He might be quite intrigued. Harry Potter is from a magical world himself, and seeing the different magical concepts and adventures in Percy Jackson fanfiction could be fascinating for him. He could compare and contrast the two magical universes, like how the magic is used, the different mythologies involved, and the types of challenges the characters face.
Most Percy fans would probably be outraged. Percy and Annabeth have a very special relationship in the original story, and fans are quite attached to it. This kind of fanfiction would seem like a betrayal of that relationship.
Annabeth would likely be one of his main allies. She's smart and resourceful, and her knowledge of architecture and strategy would be useful in building and defending Rome. Also, Grover could be there. His ability to communicate with nature could help in various ways, like finding hidden passages or getting help from nature spirits.
They'd probably be shocked. Grover, for example, would be very confused as he knows Percy well and Artemis is a goddess. Annabeth would likely be angry and feel betrayed since she has a close relationship with Percy. They might also be worried about the consequences of such an encounter, both in terms of how the gods would react and how it would change Percy as a person in the fanfiction world.
Perhaps it could be a vision of the world being completely overrun by the Titans or other powerful enemies and him being powerless to stop it. Percy has always been a hero, and the thought of failing in such a big way could be a terrifying boggart.