There could be some house - elves involved too. Maybe Dobby appears in the bathroom to offer Harry some help or advice, which would be a rather comical situation considering Harry is in the shower. Or other house - elves who are cleaning the bathroom while Harry is in there and he has some sort of interaction with them.
It's possible that some of the professors could make an appearance. For instance, Professor McGonagall might be looking for Harry because he's late for class. She could be knocking on the bathroom door while Harry is still in the shower, and he has to quickly get out and get dressed while trying to come up with an excuse for his tardiness.
In some Harry Potter fanfiction, a'morning shower' could be a simple, everyday scene used to show a character's routine. For example, Hermione might take a quick morning shower before starting her day full of studying at Hogwarts. It can also be a moment of self - reflection for a character, away from the chaos of magic and spells.
Hermione could be involved. She might be the one who comes to check on Harry because he's been in the shower for a long time. She could be worried that something's wrong, like if a dark spell has been cast on him. And when she knocks on the door, Harry has to quickly figure out how to respond while still being in the shower.
Obviously, Harry Potter himself. And there could be Dumbledore, who might guide Harry in this new path related to Merlin. Also, Hermione and Ron could be there, either helping Harry or being a bit skeptical about this new adventure.
Obviously, Harry Potter himself. Then there would be his friends like Ron and Hermione. They would be there to support Harry and also be amazed by his new powers. Dumbledore would surely be in the story as he is an important figure in Harry's life. And of course, the villains like Voldemort and his Death Eaters who would be the antagonists against Harry's newfound abilities.
Obviously, Harry Potter himself. Then there would be his friends like Ron and Hermione. They would probably play important roles in helping Harry understand and deal with his new identity as the son of Leonidas. Dumbledore would also be there, perhaps guiding Harry on how to use his newfound heritage for the greater good. And of course, there would be antagonists too. Voldemort would still be the main bad guy, and he might be even more interested in Harry now that he has this unique heritage.
One of the main characters would be Harry Potter himself. As for the Creepypasta side, Slenderman is a very likely character. He is often portrayed as a powerful and mysterious figure in the Creepypasta world. Another could be Eyeless Jack. He might be interested in Harry's magic or see him as a potential threat.
Obviously, Harry Potter himself. There could also be a new character who is like a raven - guardian, someone who has been watching over Harry because of his raven heritage. And perhaps some old characters like Hermione and Ron might play a role in helping Harry understand his new identity.
Well, Harry Potter is a given. Hecate, as his mother in this fanfiction concept. His friends Hermione and Ron would be key characters as they always are in Harry's story. There could be magical professors at Hogwarts who notice the changes in Harry due to his new heritage. Additionally, there could be some minor characters from Greek mythology, like nymphs or satyrs, that make an appearance. There might also be some descendants of other gods or goddesses who either befriend or oppose Harry based on his relation to Hecate.
Harry Potter is the central character. There may be a wise old sea - turtle wizard who imparts important knowledge to Harry. Some sea - nymphs could be characters that either help or hinder Harry. Neville could also be part of the story, perhaps using his plant - based magic in a new way underwater to help Harry in his quest to be the king of the sea.
He could meet the Dalton students. They might be very different from his Hogwarts friends, maybe more focused on academic magic in a different way.