There could be many interesting fanfictions involving Harry Potter and a snake. Maybe the snake is a magical creature with special powers that helps Harry in his adventures. For example, it could lead him to hidden secrets or protect him from dark wizards.
Perhaps he could speak Latin. Latin is often associated with magic in many fictional universes, including the Harry Potter universe. It's possible that instead of English, he has a deep understanding of Latin for casting spells and studying ancient magic texts. For example, many spells in the real Potter series have Latin roots, so in this fanfiction, he might directly use Latin in his daily magic use.
It could also be a snake from the Forbidden Forest. There are many unknown and mysterious creatures in there. A snake from that forest might be more in tune with the natural magic of Hogwarts. Harry, being the curious and kind - hearted person he is, might come across it during one of his adventures in the forest and start a friendship with it.
It could be Nagini. Even though in the original series she was more of a servant to Voldemort, in the fanfiction, she could have a different personality and form a bond with Harry.
Maybe it's an anonymous gift from someone who has been observing Harry. This person could be a former student of Hogwarts who has a special connection to snakes and sees that Harry has a kind heart and would take good care of the snake. So they leave the snake for Harry to find with a simple note that just says 'For Harry Potter'.
The snake's help could represent an unexpected alliance. In the Harry Potter series, snakes are often seen as symbols of Slytherin, which is usually at odds with Harry. So it's significant as it breaks the stereotype of enmity between Gryffindor (represented by Harry) and Slytherin.
The snake might use its ability to move stealthily. It could spy on the enemies for Harry Potter. For example, it can slither into hidden places where humans can't easily reach and gather important information.
Yes, it is possible. Fanfiction often takes creative liberties. Writers might choose to have Harry Potter speak only Latin for various reasons. Maybe they want to explore a different aspect of his magical education, as Latin is often associated with magic in the wizarding world. It could also be a way to make the story more unique or to tie in with some ancient magic plotline.
Well, in some versions of this fanfiction, Harry might discover it by accident. For example, he could be in a situation where he's near a dragon and instead of the usual fear or aggression from the dragon, it seems to be communicating with him in a strange way. Maybe the dragon's eyes seem to be trying to convey a message, and Harry just somehow understands it, like he has an innate sense that he can pick up on the dragon's thoughts.
Snake magic in Harry Potter fanfiction can be used to show a character's dark side. Since snakes are often associated with Slytherin and dark magic in the original series, in fanfiction, a character using snake magic might be on a path towards the dark arts. For example, they could use snake magic to control others or gain power in a more underhanded way.