Yes, there are quite a few. You can start by looking on fanfiction websites like Archive of Our Own or FanFiction.net. Just search for the key terms 'Harry Potter Justice League Harem' and you'll likely find some interesting reads. However, the quality can vary greatly, so it might take some time to find one that really suits your taste.
One common theme is the clash of different worlds. The magical world of Harry Potter and the superhero - filled world of the Justice League coming together. Another theme is often the development of relationships within the harem, like how different characters interact and form bonds. And there's usually some kind of adventure or conflict that the characters have to face together.
First, you need to do your research on both universes. Know the characters, their powers, and their personalities well. For the harem part, decide which characters will be part of it and how their relationships will develop. Maybe start with a plot device like a magical object that links the two worlds. Then, gradually introduce the characters to each other. Write engaging dialogues that show the different cultures of the two universes.
In a 'Harry Potter Harem Justice League Fanfiction', it could start with Harry being transported to the Justice League's universe. He discovers that his magic is a unique power there. The harem might form as the female members of the League, like Hawkgirl and Black Canary, are intrigued by this new 'wizard' in their midst. Meanwhile, they all figure out that an old enemy of the League has teamed up with Death Eaters from Harry's world. So, they train Harry in their ways and he teaches them some magic, all while dealing with the budding relationships.
It could be a combined force of Voldemort and one of the major Justice League villains like Darkseid. Voldemort might be attracted to Darkseid's power and they form an alliance. Their goal could be to take over both the wizarding world and the world where the Justice League exists. They would use their combined magic and super - villain powers to create chaos and destruction.
A possible plot could be that a villain from an unknown dimension is using the power of a lemon - like object to create chaos in both the Justice League's universe and the Harry Potter world. The Justice League and the main characters from Harry Potter have to team up to stop this villain. During their journey, they find that the lemon has some unique properties that bind them together in a way that creates a harem - like situation. For example, it could be that the lemon gives off a scent that makes characters more attracted to each other, leading to unexpected romances between characters from different universes.
If we consider the harem aspect first, perhaps there's a powerful character who has the ability to draw characters from both the Justice League and Harry Potter series into their 'harem'. The 'lemon' could be part of a magical or scientific experiment that links these two disparate universes. For instance, it could be a lemon - shaped device that opens portals between the two worlds. And in this new combined world, the characters have to navigate their relationships and powers while dealing with the challenges that come with this strange new setup.
A Harry Potter and Justice League harem fanfic could start with a portal opening between the two worlds. Characters like Harry Potter himself might find himself in the world of the Justice League, or vice versa. The harem part could play out in different ways. Maybe Superman, being the noble hero he is, finds himself in a situation where he has to protect multiple female characters from both universes. And as they spend more time together, feelings start to develop in a complex web of relationships. It would be a unique take on the crossover genre, exploring both the action - packed aspects of the Justice League and the magical elements of Harry Potter while adding the interesting dynamic of a harem.
Another concept is that the magic from the Harry Potter series starts to seep into the DC universe where the Justice League operates. This causes chaos as the laws of physics in the DC world are disrupted. The Justice League has to seek help from Hogwarts professors to understand and contain this new form of magic energy. Superman might be intrigued by the idea of magic being a new power source or a new threat he can't easily overcome with his super strength.
One way it could work is by having the magical elements of Harry Potter in the Justice League universe. For example, the wizards could help the Justice League with their spells in battles against powerful foes. Maybe Harry Potter himself could use his Patronus charm to fend off some of the League's enemies like Darkseid's minions.