I don't know for sure as I haven't read this particular fanfiction, but usually in fanfiction, Percy could be a character from a popular book, movie or TV series.
I'm not sure who Percy specifically is without reading the fanfiction. It could be an original character created by the author, or perhaps a reimagined version of a known character from a particular franchise that the fanfiction is based on.
Percy in 'percy sings fanfic' could be a local singer or an amateur performer who decided to take on the interesting task of singing fanfic. Maybe it's a stage name, or it could be someone within a small community of fans who is known for this unique activity. Without more context, it's difficult to say for sure who this Percy is.
Past Percy is likely to be more impulsive. He hasn't faced as many challenges yet and might act before thinking. Future Percy, on the other hand, would be more cautious and calculating, having learned from past experiences.
In Percy tired fanfiction, Percy often shows signs of physical exhaustion. His usual energetic actions might be slower, like his sword - fighting skills not being as sharp. For example, in some fics, he might stumble during a fight instead of his usual confident moves.
Well, in many fanfics, Percy might be depicted as having a conflicted relationship with bloodbending. He could be shown as initially reluctant to use such a powerful and somewhat dark ability.
In this fanfiction, Percy is likely a character who has been given the role of the king of monsters. Maybe he has some special powers or a unique backstory that led to this status.
It could also be Percy Weasley from the Harry Potter series. He's a Gryffindor and has his own personality quirks. Fanfic writers might focus on his intelligence, his loyalty to his family and friends, and his role in the wizarding world to make him the 'hottest guy' in their fanfictions. There are many aspects of his character that can be explored and enhanced in fanfiction to give him that 'hot' quality.
Percy is likely a main character in this fanfic. Without more context, it's hard to say exactly who he is, but he could be a character with unique abilities or a special role within the story's world. Maybe he's a hero or an anti - hero.