It could involve Harry Potter taking a stand against a dark wizarding family that has wronged his loved ones. Maybe they've targeted his friends or family, and he decides that a blood feud is the only way to deal with their ongoing threats and attacks.
Perhaps in this fanfiction, there has been a long - hidden secret about his family's past that has led to the declaration of the blood feud. For example, an old vendetta between the Potter family and another powerful family resurfaces, and Harry, having grown tired of being on the defensive, decides to go on the offensive with this blood feud. He might start by cutting off all relations with that family and then begin to expose their dark deeds to the wizarding world.
It could be a long - lost relative of Voldemort. Maybe a distant cousin or something who has the same thirst for power and has decided to target Harry and his friends to gain more influence in the wizarding world.
Perhaps in this fanfiction, Harry Potter declares war because he discovers a new and even more dangerous threat that the wizarding world has been ignoring. He realizes that the only way to deal with it is to take a stand and fight. So, he uses his influence and skills to form an army and begins a full - scale war against this new enemy, which might be a powerful dark wizard from a far - off land or an ancient evil that has been awakened.
Well, it could be about Harry trying to resolve a long - standing blood feud within the wizarding world. Maybe he discovers some dark secrets related to the feud that date back generations and uses his skills and influence to bring the feuding parties to the negotiating table.
A possible plot could involve a long - forgotten blood feud being reignited when a powerful magical artifact related to one of the families is discovered. This could lead to a race between the two families to claim the artifact, with Harry and his friends getting caught in the middle trying to prevent chaos. For example, if the artifact has the power to either destroy or strengthen a family's magic, both sides would be desperate to get it.
Obviously, Harry Potter himself could be a central character. He might be drawn into the blood feud because of his reputation and his desire to maintain peace in the wizarding world. He could try to mediate between the feuding families.
Well, it could start with an old, long - forgotten grudge between the two families. Maybe a misunderstanding in the past regarding magic or a family heirloom. For example, a powerful magical item that was thought to be stolen by a Potter from a Weasley ancestor, which led to the start of the feud.
Hermione and Ron would surely be his top allies. Hermione with her vast knowledge of magic and Ron with his loyalty and combat skills. They've been with Harry through thick and thin. Also, the members of the Order of the Phoenix like Sirius Black (if he's still alive in the fanfiction), Lupin, and Moody could be great allies. They have experience and are very powerful wizards.
One idea could be that the blood test is a school project at Hogwarts. Students are required to do a detailed analysis of their own blood magic. Hermione would be super - excited and dig deep into research. Harry might be a bit worried as his blood has some unique connections to Voldemort. Ron, on the other hand, could discover something unexpected about his Weasley bloodline that has been lost in history.
Well, perhaps it could be about Harry being injured in a battle and coughing up blood. Maybe he's in a fight with a dark wizard and gets seriously hurt.
Well, it could be that Harry gets tired of Umbridge's tyrannical rule at Hogwarts. He might start by secretly organizing the students to resist her unfair rules. Maybe he uses his status as the Boy Who Lived to inspire others. For example, he could encourage students to defy her ban on certain magical activities. Then, he might start a campaign of small acts of rebellion, like writing anonymous letters about the truth of what's happening in the school.