In some fanfictions of 'harry discovers magic early', he might accidentally perform magic in front of the Dursleys much earlier than in the original story. This could lead to either extreme fear or a strange kind of acceptance from them. Maybe they try to hide it from the wizarding world for their own gain. For example, Vernon might see it as a way to make money if he can control Harry's magic.
Another plotline could be that Harry's early discovery of magic makes him more confident when he finally arrives at Hogwarts. Since he has already had some experience with magic, he might be quicker to learn spells and be more adventurous in exploring the magical world. He could also form different relationships with his classmates because they see him as someone who already has a head start in magic.
One interesting scenario could be Harry accidentally performing magic in front of the Dursleys much earlier than in the original story. For example, he might make Dudley's pudding float right in front of their eyes, which would lead to a huge commotion in the household.
One interesting plot could be Harry accidentally using magic in front of Muggles before he goes to Hogwarts. This would create a whole new set of challenges as the wizarding world would have to cover it up to avoid the Statute of Secrecy being broken.
Obviously, Harry Potter himself is the central character. Then there's Dumbledore, who might be even more vigilant in protecting Harry earlier due to his early magic display. Hermione could also be involved, perhaps being even more intrigued by Harry's early magical experiences and trying to study them.
Obviously, Harry Potter himself is the central character. Then there are often the Dursleys, who would have to deal with Harry's early magic in different ways. Sometimes, Hagrid might also be involved earlier, coming to rescue Harry from the chaos caused by his early magic manifestations.
Well, Harry Potter himself is surely one of the main characters. Since it's about him discovering magic early, he'll be at the center of the story.
One interesting plotline could be Harry having unique magical abilities that are even more powerful than in the original books. For example, he might be able to control time in ways not seen before.
One interesting plotline could be a character discovering a new form of shadow magic that has been long forgotten in the wizarding world. This could lead to a race against time to master it before the dark forces do.
One interesting plotline could be Harry using his unique experiences as a student at Hogwarts to reform the Ministry. For example, he might create more fair laws regarding magical creatures, having befriended so many during his school days. Another could be his struggle with the pure - blood supremacist factions within the Ministry, trying to change the old - fashioned views that have long been ingrained there.
One interesting plotline could be the discovery of a new, hidden magical ability that the heir of magic possesses. This ability might be something that even Voldemort didn't know about and could turn the tide in battles against dark forces. Another could be the exploration of the heir's family history, uncovering secrets that have been long buried in the wizarding world. For example, they might find out that their family had a connection to an ancient and powerful magical artifact that could change the balance of power in the wizarding community.
In this type of fanfiction, a great plotline could be that Harry stumbles upon a hidden family grimoire. Inside, he finds magic that was thought to be lost. For example, there could be spells for creating protective shields that are stronger than any known spell. Or perhaps he discovers family magic that is related to time - travel, which he then has to learn to control carefully so as not to disrupt the timeline. This discovery of family magic would add a whole new layer to his character development and his role in the wizarding world.