Common themes often revolve around the origin and nature of the 'blood god'. Writers may explore how this entity came to be in the Harry Potter universe. Another theme is the impact on the wizarding society. The 'blood god' could disrupt the existing order, leading to themes of chaos and restoration. There may also be themes related to sacrifice, as characters might have to give up something to deal with the 'blood god' situation. In addition, themes of loyalty are often explored as characters choose sides in the face of this new and often dangerous element in the story.
One common theme could be power struggles. The 'blood god' concept might introduce a new source of power, leading to characters vying for control. Another theme could be the exploration of dark magic. Since it involves a 'blood god', it's likely that dark and forbidden magic plays a role. Also, there might be themes of redemption or corruption as characters interact with this new and powerful entity.
Often, there's the theme of mystery. The origin and nature of giant blood can be a mystery in fanfiction. It might be something that the character has to discover about themselves. Maybe they start to notice strange abilities and have to figure out if it's related to their giant blood. Also, the theme of loyalty can come into play. If there are groups that are against those with giant blood, a character might have to decide where their loyalty lies - with their own kind or with the wizarding society that may not fully accept them.
Power and its implications can be a theme too. Their 'blood brother' bond might give them access to unique powers or make them a target for those who want to use their power. This can lead to a lot of conflict and drama in the fanfiction, as they have to deal with the consequences of having this special bond.
Family heritage is another theme. Since blood is related to family, many fanfictions explore how blood magic is tied to one's family lineage and the secrets that come with it. For example, a character might discover a long - lost family magic through blood magic. It also often delves into the darker aspects of magic, as blood magic is usually considered a more dangerous and morally ambiguous form of magic in the Harry Potter universe.
One common theme is power. Since Harry is the son of God, he often has enhanced or different magical powers. Another theme is identity. Harry has to grapple with his new identity as the son of God on top of being a wizard. Also, there's the theme of destiny. His role in the wizarding world and perhaps in a larger cosmic sense is redefined.
One common theme is power and its consequences. If a character is the 'god of magic', they have to deal with the great power they possess. Another theme could be the exploration of the origin of magic. Since they are a 'god of magic', they might be involved in uncovering the very source of magic in the wizarding world. And also, there's often the theme of destiny, like if it was the character's destiny to become the 'god of magic' and what that means for their future and the future of the wizarding world.
Another theme is the discovery of new magic. With the merging of two different magical concepts, fanfiction often features characters exploring new forms of magic that are unique to this combined universe. For example, spells that are a combination of Hogwarts magic and the powers of the demigods. This makes the stories exciting as readers get to see something new and different.
One common theme is the discovery of a hidden power within the blood. It often leads to a journey of self - discovery for the character. For example, they might find out they can do things that no one else can because of their blood - gift.
One common theme is the integration of magic systems. Since Harry Potter has its own magic and the Olympian gods have their own powers, these fanfictions often find ways to blend them. Another theme is identity. Harry has to figure out his new identity as a god - like figure on top of being a wizard.
One common theme is power struggle. Since you have a vampire god involved, there's often a fight for power or control. Another theme is the clash of different mythologies. The magic of Harry Potter world collides with the vampire lore which has its own set of rules and beliefs.
Power corruption is a common theme. When Harry becomes a 'dark god', it often shows how power can change a person. Another theme is the redefinition of good and evil. In these fics, the traditional view of good and evil in the Harry Potter universe is often challenged. Also, there's the theme of isolation as Harry's new path might lead him to be separated from his former friends and allies.