Hermione would likely be very curious about Anastasia. She might study her as if she were a new and interesting magical creature. Hermione would probably ask Anastasia a million questions about her Muggle life and try to understand how she thinks.
One idea could be that Anastasia Steele somehow gets transported into the Harry Potter world. Maybe she has a unique ability that catches the attention of the Hogwarts professors. For example, her tenacity and strong will, which were prominent in her own story, could be seen as a form of magical resistance or inner strength in the wizarding world.
Elena could be an antagonist. Since she has a history with Christian, she might try to interfere with Anastasia's pregnancy, perhaps out of jealousy or a desire to maintain some control over Christian.
The characters would interact in very strange ways. The Hogwarts students would be shocked by the Jackass crew's behavior. The Gryffindors might be initially intrigued, while the Slytherins would be disdainful. Harry and his friends would probably try to keep the Jackass guys out of trouble, but it would be difficult as they are always looking for the next wild thing to do.
Harry might be in awe of Elsa's powers at first. He would likely approach her with caution and respect, as he does with most powerful beings. Elsa, on the other hand, would be curious about Harry's world of wands and spells. They could start by sharing their stories. Harry would talk about Voldemort and his battles, and Elsa would share her experiences with her frozen kingdom and her isolation.
Well, Ron might be initially terrified of Slenderman. But when his friends are in danger, he would step up. The Weasley twins could try to play pranks on Slenderman, not fully realizing the danger at first. Dumbledore, on the other hand, would be very cautious. He might observe Slenderman from a distance, trying to understand his nature before taking any action. In a 'Harry Potter and Slenderman fanfic', these interactions would create a lot of interesting scenarios.
The Stargate characters are used to dealing with advanced technology and alien cultures. When they meet the Harry Potter characters, they might be initially confused by magic. For example, Jack O'Neill might be both amused and intrigued by the spells the wizards cast. Meanwhile, Harry Potter and his friends would be curious about the Stargate technology and the different worlds it can access.
The Avengers could be impressed by the magic of the Harry Potter characters. For instance, Captain America might be in awe of the Patronus charm. And the Harry Potter characters could be amazed by the Avengers' superpowers. Hermione might be very interested in Bruce Banner's scientific knowledge.
One great fanfic could be 'A New Beginning for Christian and Anastasia'. It might explore their relationship further after the events in the original story, like how they handle family life together.
One idea could be exploring how Anastasia and Christian deal with the pregnancy in the context of their complex relationship. Maybe there are doubts and insecurities that surface.
They could be classmates. For example, if the OC is in Gryffindor, they can study with Harry, Ron, and Hermione, participate in Quidditch practice together, and get into adventures in the Forbidden Forest. Or they could be rivals, like an OC from Slytherin who always tries to outdo Harry in every magical test or duel.