Well, one possibility is that Harry would face a huge internal conflict. On one hand, he's a wizard, on the other, he has this heritage of a witch hunter in his blood. He might struggle with the idea of magic being 'good' as he's been taught all his life by the wizarding world that magic is wonderful, but his witch hunter ancestry could make him question it. Maybe he'd start to investigate the darker sides of magic more closely, trying to find a balance between what he's always known and what his heritage implies.
His relationship with Hermione would become more complex. Hermione, being a firm believer in the rights of wizards and the value of magic, might be initially suspicious of Harry. She'd worry that his witch hunter heritage could cloud his judgment. However, as they've been through so much together, she'd also be one of the first to try and understand him. She might start researching about witch hunters to see if there's a way to reconcile Harry's two sides.
Perhaps a witch who has lost her family to witch hunters decides to take matters into her own hands. She disguises herself as a Muggle and tries to infiltrate the witch hunter's group to take revenge. This would make her a very interesting and complex main character.
One great 'Harry Potter and The Last Witch Hunter' fanfiction is 'The Crossover Chronicles'. It combines the magic of Harry Potter's world with the gritty, dark elements of The Last Witch Hunter. It has an interesting plot where Harry Potter teams up with the Witch Hunter to fight a new, powerful dark force that threatens both their worlds.
A plot could involve a group of witch hunters infiltrating Hogwarts. They think there are dark witches there, but they end up getting lost in the magical castle and start to see the beauty and positive aspects of magic. As they interact with students and teachers, they have to re - evaluate their views on witches and magic in general.
One of the most creative crossovers is the idea of a magical school in the world of The Last Witch Hunter, inspired by Hogwarts. In this fanfic, Witch Hunters' children start to attend this school, and they learn both traditional Witch Hunter skills and magic from the Harry Potter universe. It's a great mix of the two worlds' educational systems and magic concepts, and it shows how the two different cultures can blend together.
Perhaps a new type of creature that is neither from the Harry Potter world nor the Witch Hunter's world. It could be a result of some dark magic experiment gone wrong. This creature could have the ability to nullify magic in some ways, which would be a huge threat to both Harry and the Witch Hunter.
A fanfiction could explore what would happen if the magic from the Harry Potter universe was somehow combined with the powers of the Last Witch Hunter. For example, the Last Witch Hunter could gain the ability to use spells like Harry Potter, or Harry could get some of the unique skills of the Witch Hunter. This would lead to a whole new set of adventures and challenges for them both.
There might be. A lot of fanfiction writers come up with really creative ideas, and the concept of a Harry Potter character being a descendant of Raizen has potential for an exciting story. However, it may not be as common as some other fanfiction themes, so you might have to do a bit of digging. Try not only the big fanfiction platforms but also some smaller, niche Harry Potter fanfic communities.
In a Harry Potter fanfiction, a Ravenclaw descendant might be a brilliant young wizard who is having a hard time fitting in at Hogwarts. They are constantly underestimated because they are from a less - known Ravenclaw family line. But as the story progresses, they use their Ravenclaw - like intelligence to solve a mystery that has been plaguing the school for years.