One possible theme could be transformation. The girl being filled with water might symbolize a change, like a metamorphosis into something new or different.
I'm not sure specifically which 'girl filled with water' fanfic. You could try searching on some popular fanfic platforms like Archive of Our Own. They have a vast collection of various fanfics, and you might be able to find something related by using relevant keywords in their search bar.
Perhaps in a more symbolic or magical sense, water could be a source of power for the teen girl. If it's a fantasy - based fanfic, the water could be an element that she has been filled with, like she has absorbed the power of water and can use it in some way, such as for healing or for combat. This would make for an interesting character arc in the fanfic.
Fanfic varies widely in themes and concepts. However, the 'teen girl filled with water' description is rather unusual. It could potentially be part of a more complex and symbolic story. Maybe look for stories that involve water elements and teen girl characters and see if you can find something that fits the bill. You might also consider creating your own fanfic if you can't find an existing one.
One possible plot could be that Hogwarts is flooded due to a spell gone wrong. Harry and his friends have to use magic to navigate through the water - filled corridors, while also trying to figure out who cast the spell. Maybe they discover it was a first - year student who accidentally unleashed an ancient water - summoning charm from a forbidden book.
The Hogwarts ghosts would be rather amused by the whole situation. Peeves, the poltergeist, would be causing even more trouble, perhaps making waves in the water or using it to play tricks on the students. Meanwhile, Hagrid would be concerned about the magical creatures on the grounds. He'd be trying to find ways to keep them safe from the rising water, and might even try to use his giant strength to build makeshift dams or barriers.
One main theme could be transformation. When Harry is filled with water, it might symbolize a change in his character or abilities. For example, he could become more fluid in his thinking or more adaptable, just like water.
A novel that was filled with water usually referred to those novels that were empty in content, lacked creativity, were repetitive, and had bland plots. These novels may repeat the same plot, characters, and scenes in large numbers. The lack of depth and cohesiveness makes people feel bored and bored. In addition, novels that were filled with water often had serious plot loopholes and logical errors that made readers feel confused and disappointed.
In order to avoid writing a novel that was full of water, he tried to make the story more interesting and fascinating. At the same time, it was also necessary to pay attention to character shaping and emotional expression so that the characters had a distinct personality and depth so that the readers could truly understand and resonate.
One popular 'Harry filled with water' fanfiction might be 'The Watery Adventure of Harry'. It's a story where Harry gets caught in a magical rainstorm that floods the Hogwarts grounds and he has to use his magic in unique ways to deal with the situation.