A new character could be introduced as the lord. Maybe a transfer student from a different wizarding school who has a unique set of skills and qualities that make them suitable to lead multiple houses. This character could bring in new ideas and ways of thinking that would shake up the traditional Hogwarts house system.
Hermione Granger would also be a great candidate. She is highly intelligent like a Ravenclaw, but her loyalty to her friends and the fight against evil shows Hufflepuff traits. Her courage in the face of danger is Gryffindor - like, and she has proven to be cunning when outwitting her enemies, which is a Slytherin quality.
Maybe it's a well - known character like Hermione. Given her intelligence and leadership skills, she could be thrust into a situation where she becomes the lord of many houses. She would then use her knowledge of magic and her ability to make friends across different groups to manage the houses effectively.
It could be a dark wizard who also has some form of time - related power. Maybe he wants to use time to his advantage to take over the wizarding world. For instance, he could go back in time to eliminate the founders of Hogwarts so that he can rewrite the rules of magic for his own evil purposes.
The Order of the Phoenix would definitely be potential allies. They have experience in fighting dark wizards and would be quick to recognize the threat of the Shadow Lord. Their members, like Sirius Black (if he were still alive in the fanfiction), could offer their unique skills and knowledge.
One idea could be a character who has to balance the different cultures and traditions of the multiple houses they are lord of. For example, Gryffindor's courage, Ravenclaw's intelligence, Hufflepuff's loyalty, and Slytherin's cunning all come with their own sets of values and expectations.
In a 'Harry Potter Lord of Many Houses' fanfiction, it might involve a time - travel element. A character from the future goes back in time and becomes the lord of many houses. They use their knowledge of future events to make changes in the houses. They could reform the house systems, introduce new magical teachings, and change the way the houses interact with each other, all while facing resistance from traditionalists within the wizarding community.
Hermione could be one of the characters in the harem. Her intelligence would be an asset to Harry, even as a Dark Lord. She might be torn between her loyalty to the original Harry she knew and her feelings for this new, darker version. Ginny could also be part of it. Given her connection to Harry in the original story, her presence in the harem could add an interesting dynamic, especially if she tries to change Harry back to his old self.
Potential characters could range from the well - known witches at Hogwarts to those from other magical institutions. Fleur Delacour could be in the harem, given her beauty and magical abilities. And there could be characters from the wizarding world outside of Britain too. Maybe a Japanese wizard or witch who has unique magical techniques and is drawn to the Harem Lord's power and charisma.
Hermione Granger is also popular. In fanfiction, she could be using her intelligence to come up with new ways to improve the relations between the houses, perhaps by creating study groups that include students from all houses.
A new character could be introduced as a Sith Lord. Maybe a wizard who has been studying dark and forbidden magic from other dimensions. He could have a red lightsaber - like wand and use powers that combine magic and Sith - like abilities. For example, he could use mind control not just on muggles but also on some weak - willed wizards.
It could also be an existing character from the Harry Potter series like Hagrid. Given his love for all creatures, including some that are considered dangerous, he could be at the center of a story about the 'Lord of Dark Creatures'. He might be trying to protect these creatures from those who would use them for evil purposes or trying to rehabilitate them.