Another plot could be that Supergirl is mistaken for a new type of magical being in the Harry Potter universe. The Ministry of Magic tries to capture her for study, but she teams up with the Weasley twins, who see her as a source of great fun and chaos. Together, they play pranks on the Ministry officials while also trying to figure out how to get Supergirl back to her own world.
One possibility could be that Supergirl somehow ends up in the wizarding world of Harry Potter. Maybe she's chasing a powerful magical artifact that has fallen into the wrong hands in Hogwarts. She could use her superpowers to help Harry and his friends during a particularly tough battle against Voldemort, like using her heat vision to fend off Dementors or her super strength to break through some dark magic barriers.
Perhaps a plot where Hermione discovers Supergirl's existence and is intrigued by her non - magical yet extremely powerful abilities. She starts researching ways to combine magic and Supergirl's powers for the greater good. This could lead to some really interesting experiments and adventures, with Ron being a bit skeptical at first but eventually coming around as they see the potential of such a combination.
A plot could revolve around a love triangle. Supergirl catches the eye of both Harry Potter and Draco Malfoy. Harry is attracted to her because of her strength and kindness, while Draco is intrigued by her otherworldly nature. Supergirl is more interested in Harry because of his selfless nature. This causes tension between Harry and Draco, which is further complicated by the fact that they have to work together to stop a new threat to the wizarding world. The lemon aspect could be some tender moments between Harry and Supergirl as their relationship develops.
A 'Harry Potter marries Supergirl' fanfiction might start with Supergirl accidentally landing in the wizarding world. Harry Potter, being the curious and brave wizard he is, approaches her. At first, there are misunderstandings due to their different cultures and powers. But as they start to communicate and learn about each other's worlds, they realize they have a lot in common. They both fight for the good of their respective worlds. This mutual understanding leads to a deep friendship and later, love. Their marriage would be a grand event, attended by wizards, witches, superheroes, and supervillains (the ones who are allowed to come under a truce). It would symbolize the coming together of two very different yet equally amazing fictional universes.
Well, it could be that Supergirl lands in the wizarding world somehow. Maybe she's chasing a bad guy who uses magic to escape to Hogwarts. And then she teams up with Harry Potter to fight the bad guy. Harry could teach her about magic while she teaches him about her superpowers.
One possible plot could be that fem Harry Potter somehow ends up in the Supergirl universe. She uses her magic to help Supergirl fight against a powerful villain who has a weakness to magic. Along the way, she has to adapt to the new world and its rules.
One idea could be that Supergirl lands in the wizarding world by accident. She might be initially confused by the magic there, but her superpowers could also offer a new perspective on magic. For example, she could use her heat vision to enhance a spell or her super strength to protect Hogwarts from a new dark threat that the wizards alone can't handle.
One idea could be that during a Quidditch match, a player gets seriously injured. Instead of using magic to heal right away, an ambulance from the Muggle world is called in by a confused bystander. The ambulance crew has to deal with the magical aspects they've never seen before while trying to transport the patient to a Muggle hospital. This could lead to a lot of comical and also tense situations as they try to figure out how to handle the situation.
One idea could be a wizard discovers Beyblades in the Muggle world and decides to bring them to Hogwarts. He then challenges his classmates to Beyblade battles instead of duels. The different houses could form their own Beyblade teams and compete in a tournament, with the winning house getting extra house points and a special magical Beyblade as a prize.
One idea could be Harry using parkour skills to escape from the Death Eaters in the Forbidden Forest. He jumps from tree to tree, slides under fallen logs, and uses his magical abilities in combination with his newfound parkour skills to outmaneuver them.
One idea could be that Voldemort discovers the power of the Stargate and tries to use it to gain more power. He could send his Death Eaters through the Stargate to conquer other worlds and bring back resources or powerful artifacts to help him in his quest to take over the wizarding world. The Order of the Phoenix would then have to follow through the Stargate to stop him.
One idea could be that the Justice League somehow ends up in the wizarding world. Maybe a magical portal opens during a battle in their universe and sucks them into Hogwarts. Superman's powers could be affected by the magic there, and Batman would be intrigued by the complex magic system and start studying it. Harry Potter and his friends could team up with the Justice League to fight a new dark force that threatens both the magical and non - magical worlds.