One interesting plot could be that Harry turns into a stag, just like his father's Patronus. He could then use this form to explore the Forbidden Forest in ways he couldn't as a human. He might discover hidden magical creatures or ancient secrets. Another plot could be that he turns into a cat and has to navigate Hogwarts corridors without being noticed by Filch. He could also use his new form to spy on Snape and find out if he's really up to no good.
Another interesting concept is Harry turning into a cat. He could then slink around Hogwarts unnoticed. He could spy on Snape or Malfoy, gathering information. His cat form would give him the ability to be stealthy and get into small spaces, like the hidden passages in the castle.
One great fanfic could be 'Harry's Animal Form Adventures'. In this, Harry turns into a stag, just like his Patronus. It has really interesting scenes where he uses his new form to explore the Forbidden Forest in ways he couldn't as a human. Another is 'The Animagus Harry', where he discovers his ability to turn into different animals depending on his emotions. For example, when he's angry, he turns into a small but fierce badger.
One interesting plot could be the main character's struggle with their new dragon form. For example, they might have trouble controlling their newfound powers like breathing fire or flying. Another plot could involve the character trying to hide their dragon identity from their friends and family at first. Or perhaps there's a plot where the dragon - turned character has to face off against an ancient dragon - slaying order that is hunting them.
One idea could be that Harry has to hide his new werewolf form from his friends at Hogwarts. He might struggle with the stigma associated with werewolves in the wizarding world, even though his friends know him well. Another could be that he discovers new magical abilities related to his werewolf form that help him in his fight against Voldemort. For example, enhanced senses that allow him to detect dark magic more easily.
One interesting plot could be the characters going on a magical camping trip during the vacation. They might encounter new magical creatures in the forest that are not well - known in the original books. For example, a group of friendly forest sprites that lead them to a hidden glade filled with enchanted plants.
A plot where the village is suddenly under a dark spell and the young wizards and witches from Hogwarts have to work together to break it. They'll face challenges like deciphering ancient runes and battling dark creatures. This would be a great opportunity to see different characters' skills and teamwork.
One interesting plot could be the hunter's unique adventures within the wizarding world. Maybe he discovers hidden magical creatures that Harry Potter and his friends haven't encountered yet.
One interesting plot could be an assassin who is secretly a double agent within Voldemort's ranks. They pretend to be working for him but are actually protecting Harry Potter and his friends.
One interesting plot could be about a villager who discovers a hidden part of the island that has magical properties. Maybe there are special fruits there that give unique abilities to the villagers who eat them.
One idea could be that as a girl, Harry has to deal with different social expectations in the wizarding world. For example, she might face more restrictions on certain adventures compared to when she was male. Also, her relationships with Ron and Hermione could change in interesting ways. Ron might be more protective, while Hermione could become a closer confidant as they share more 'girl - specific' experiences.