One possible plotline could be the discovery of a new type of deadly snake in the Forbidden Forest that has some mysterious connection to dark magic. Maybe the snake is guarding a long - lost artifact.
Well, perhaps the deadly snake is actually a cursed form of a once - friendly magical creature. In the fanfiction, Harry and his friends might have to find a way to break the curse. They could face many challenges along the way, like dealing with other dark creatures that are attracted to the snake's dark energy.
Perhaps the snake is a transformed wizard who was cursed. This would lead to a plot where Harry has to find a way to break the curse. He might have to go on a quest to find rare ingredients for a potion. Along the way, he and the snake face various challenges, like dark wizards trying to stop them, and they form a strong friendship through their shared experiences.
Perhaps in the fanfic, Harry is turned into a snake for a period of time. As a snake, he experiences the wizarding world from a different perspective. He has to learn how to survive as a snake while still trying to fulfill his role in the fight against Voldemort. He might encounter other snakes that are either friendly or hostile, and he has to use his wits to deal with them.
Perhaps there's a plot where a magical creature that has the appearance of a snake is disguised as a lion - like being. It could be used as a sort of spy within the Gryffindor common room. This would lead to all sorts of chaos as it tries to gather information for an unknown Slytherin - related plot.
Well, a plotline might involve the snake familiar getting into trouble. For example, it could be mistaken for a dark creature by the Ministry of Magic. Harry then has to prove that his snake is not evil. Or perhaps the snake helps Harry discover a hidden part of Hogwarts. Since snakes are often associated with secrets, it could lead him to a secret chamber or passage that no one else knows about. And this could be a key to solving a mystery or finding a powerful magical item.
Maybe the deadly sins could be personified as new characters in the Harry Potter world. These characters would try to influence the main characters to fall into sin. For instance, Lust could be a siren - like figure that tries to seduce Ron away from Hermione, causing chaos in their relationship and in the Gryffindor house.
It could still be Harry Potter himself. He has a history of facing dangerous creatures and dark magic, so it would be natural for him to take on the challenge of the deadly snake.
Some fanfictions focus on the snake as a misunderstood creature. In this type of story, the snake is constantly misjudged by the wizarding world. Harry, being the empathetic character he is, befriends the snake and discovers that it has a heart of gold. They then go on adventures together, with the snake using its unique abilities like slithering into small spaces to retrieve magical items for Harry.
In this fanfic, it could be that Harry turns into a snake as a result of a powerful transfiguration spell gone wrong. As a snake, he has to navigate the Hogwarts grounds in a new way. He might find secret passages or areas that are only accessible in his snake form. His friends, like Hermione and Ron, would then try to find a way to reverse the spell, and there could be a lot of trial and error, as well as some really heart - warming moments of friendship along the way.
Well, some might involve magical creatures with furry characteristics in new adventures at Hogwarts. For example, a werewolf character could have a unique story arc that intersects with the main Harry Potter plot. Maybe they are trying to find a cure or dealing with the prejudice within the wizarding world in a different way than what's in the original books.
One possible plotline could be a comical take on baby Harry's magical mishaps. Maybe he accidentally makes his diapers levitate or turns his crib into a mini Hogwarts. Another could be about how the other characters like Hagrid or Dumbledore interact with baby Harry in this unique situation, perhaps trying to figure out how to handle his early magical outbursts while he's still in diapers.