There could be a book of ancient runes that holds the key to powerful spells. Another might be a tome about magical beasts, which gives Harry a better understanding of how to deal with them magically. And perhaps a book on forgotten magic arts that provides him with unique ways to use magic.
One interesting book could be the 'Chronicles of Magical Inventions'. It might have descriptions of long - lost magical devices and how to use magic to operate them. This could help Harry in his adventures. There might also be a 'Book of Elemental Magics', which teaches him advanced control over the elements, like creating more powerful fire spells or stronger water - based defenses. Also, a 'Grimoire of Shadow Magic' could be in there, which, although dangerous, gives Harry an understanding of the darker aspects of magic and how to counter them.
In such fanfiction, the books could contain unique magical insights. Harry, by learning from them, might be able to combine different magics. Say, he could merge potion - making knowledge from a book with his regular spellcasting. This makes his magic more versatile and powerful. It's like he has a secret weapon in his magical arsenal that others don't.
Another idea could be Harry learning magic from a time - traveling wizard from a far - off future. This would introduce futuristic magical concepts and technologies that he would have to adapt to. It could also lead to him having to use his traditional Hogwarts magic in new and unexpected ways to keep up with the advanced magic he's learning.
One interesting story could be Harry's initial struggles. He might face challenges like accidentally causing chaos as he tries to control his wandless magic. For example, he could make objects fly uncontrollably in the Gryffindor common room. Another aspect could be his secret training sessions. He might find a hidden place in Hogwarts, like an abandoned classroom, to practice without others knowing.
There are fanfictions where he learns elemental magic in a new way. For example, being able to combine fire and water magic in a unique and powerful way that was not explored in the original books. He could use this to create new defensive or offensive spells against dark wizards.
One interesting lesson could be table manners in the wizarding world. There might be specific ways to hold a wand while dining or proper incantations to say before and after a meal. Another could be how to address different levels of wizards and witches, like the proper title for a powerful elder wizard. And perhaps the correct way to enter and exit a magical room or building, which could involve specific spells or gestures.
Maybe it could be an ancient magical being like a centaur. Centaurs are known for their knowledge of the stars and ancient magic. They might take Harry under their wing and teach him old magic that has been passed down through their generations.
One great plot development could be that the elemental magic Harry learns is not part of the traditional Hogwarts curriculum. So, he has to seek out hidden mentors or ancient texts. This could lead to him exploring parts of the wizarding world that are long forgotten. As he delves deeper into elemental magic, he might also start to question the limitations of the magic he has been taught so far at Hogwarts.
One of the interesting spells could be 'Tempestus Ignis' which creates a fiery storm in some fanfictions. It gives him a powerful offensive move against dark creatures.
Yes, it can be considered dark and controversial. Blood magic in the Harry Potter universe is often associated with dark and unethical practices. It goes against the principles of the good magic that Hogwarts teaches. For example, the use of blood in dark spells is seen in the actions of Voldemort. In fanfiction, having Harry Potter learn blood magic is a deviation from his character's usual moral stance, which can stir up a lot of debate among fans.
It could be an older relative who was thought to be dead but actually has been living in seclusion, waiting for the right time to teach Harry about their family magic. This relative might have a vast knowledge of the family's magical traditions and spells.