Well, it could be that Sparda takes Harry under his wing after seeing the boy's potential and the difficult situation he's in at the Dursleys. Sparda might train Harry in some unique ways, combining magic with his own demon - slaying skills. Harry could learn to be more self - reliant and gain a new perspective on his power.
One possible main antagonist could be Voldemort still. Even though Harry is now under Sparda's protection, Voldemort would see Harry as a threat and would try to get rid of him. Another could be some of the demons from Sparda's world who see Harry as an intruder or a threat to their plans in the new world order that Sparda is trying to create with Harry by his side.
Harry Potter himself is often a popular character in these fanfictions. He can be the one who either discovers the connection to Sparda or is the recipient of Sparda - like powers. Another popular character could be Dante from the Sparda universe. Writers might bring him into the wizarding world and have him interact with the Harry Potter characters, causing all sorts of chaos and adventure.
One interesting concept could be the merging of the magical world of Harry Potter with the demon - slaying elements of Sparda. For example, a character from the Harry Potter universe might gain the power of Sparda and use it to fight dark wizards in a new and unique way. It could also involve crossovers where characters from both worlds interact, leading to unexpected alliances and conflicts.
Another theme is the idea of hidden lineages or connections. Many fanfictions play with the idea that there is some long - lost connection between the Potter family and Lord Sparda's world. This could be through an ancient prophecy or a secret pact made generations ago. It adds an element of mystery and discovery as characters try to figure out these connections.
In a 'Harry Potter Heir of Sparda' fanfiction, the plot might involve a mysterious connection between the wizarding world and the world of Sparda. Harry could be led to an ancient prophecy that links him to the Heir of Sparda. As he delves deeper, he meets characters from the Sparda universe who teach him how to harness his new powers. He then uses these powers not only to defeat Voldemort but also to protect the entire magical world from threats that were previously unknown.
Well, it would be a really interesting mix. Sparda is from the Devil May Cry universe, a powerful demon. If he raised Harry Potter, Harry might grow up with a very different set of skills. He'd probably be trained in combat like Dante, Sparda's son. His magic could be combined with demon - fighting abilities. For example, he could use his wand to perform spells while also having the physical prowess to take on dark creatures in close combat.
Well, it could be a story full of magic and demon - slaying adventures. Harry might inherit some of Sparda's powers, like super strength and the ability to use a cool weapon. He could use his magic along with these new powers to fight against dark forces in both the wizarding world and the demon world. It would be a really unique crossover, with Harry having to balance his life as a wizard and as a son of a demon - like being.
In a 'Harry Potter Heir of Sparda' fanfiction, the main antagonist could be a combination of Voldemort and a corrupted figure from the Sparda lineage. Voldemort is still hell - bent on ruling the wizarding world. The corrupted Sparda figure might be jealous of Harry being the heir and wants to take the powers for themselves. They could form an alliance, with Voldemort providing the wizarding world knowledge and forces, and the corrupted Sparda figure bringing in their own dark powers from their world. This combined force would be a huge obstacle for Harry to overcome.
Well, it could be that Harry Potter discovers he has a connection to Sparda. Maybe he has some latent power that is related to Sparda's abilities. He then has to learn to control this new power while still dealing with the threats in his own wizarding world. And perhaps he uses his new - found powers to fight off dark wizards in a more badass way.