One possible plotline could be that the princess is from a wizarding kingdom that has been taken over by dark forces. Harry, being the hero he is, stumbles upon the situation during one of his adventures. He uses his magic skills, like the Patronus charm to fight off the Dementors that are guarding the princess. Then he and the princess have to work together to find a powerful magical artifact that can restore her kingdom.
Perhaps the princess is a Muggle - born who has some latent magical abilities. She is kidnapped by a group of dark wizards who want to use her for some dark ritual. Harry Potter gets wind of this and sets out to save her. Along the way, he has to face various challenges and spells. Once he saves her, he helps her discover her magical abilities and she decides to join Hogwarts to learn more about magic.
A plotline might involve Harry being a hidden princess all along. He discovers this truth and has to reclaim his rightful throne in the wizarding world. Along the way, he would face challenges from those who don't want him to succeed, and he would use his Harry Potter skills like magic and courage to overcome them. It could also involve a love story where he has to choose between his duty as a princess and his feelings for someone.
One possible plotline could be that Harry discovers a plot against Snape before it's too late. Maybe he overhears some Death Eaters planning to ambush Snape while he's on a solitary mission. Harry then uses his invisibility cloak and magic skills he's learned over the years to outwit the Death Eaters and save Snape. This would show Harry's growth as a wizard and his ability to set aside past differences with Snape.
Maybe Spider - Man is being attacked by some dark creatures that are immune to his usual attacks. Harry Potter arrives on the scene, having sensed the disturbance in the magical fabric. He casts protective spells around Spider - Man and then uses his Patronus charm to drive away the dark creatures. They then team up, with Harry teaching Spider - Man some basic defensive magic spells in case he faces such threats again.
One possible plotline could be that Harry travels back in time. In this scenario, he stumbles upon a young Severus Snape being bullied by some older kids. Harry, with his knowledge of Snape's future importance and his own sense of justice, steps in to save Snape. This could then lead to a change in their relationship dynamic. Instead of the animosity that exists in the original story, Snape might view Harry in a different light from the start, which could potentially change the whole course of events at Hogwarts in the future.
Well, in some fanfictions, Snape might be trapped in a magical trap set by Death Eaters who are still loyal to Voldemort's ideals. Harry, with his natural sense of justice and his loyalty to Hogwarts (where Snape also has a complex connection), figures out the trap's mechanism and manages to free Snape. Or perhaps Snape is on the verge of being attacked by a magical creature, and Harry, using his experience with magical creatures from Hagrid's teachings, scares the creature away and saves Snape.
One scenario could be that the Winchesters are trapped in a magical dimension while on a hunt. Harry Potter, with his experience in navigating strange magical places, could find a way to enter the dimension and lead them out. Another possibility is that a powerful dark wizard has set a curse on the Winchesters. Harry, being well - versed in counter - curses, would be able to break it and save them.
A plotline could be where Harry is in a wizarding duel against a powerful and evil opponent. He's outmatched and on the verge of being defeated when Greengrass steps in. She has a special magical artifact that she uses to turn the tide of the duel and rescue Harry. After that, they might embark on a journey together to find out more about the origin of the evil opponent and how to defeat them once and for all.
One possible plotline could be Harry discovers his latent archmage powers early on and uses them to quickly defeat Voldemort. Another could be that he has to go on a journey to learn how to fully control his archmage abilities while still dealing with the normal Hogwarts stuff like classes and friendships.
One possible plotline could be that Harry discovers his siren abilities during his time at Hogwarts. At first, he's confused and scared by these new powers. He might accidentally use his siren voice to make a teacher or a student do something they don't want to. Then he has to learn to control it with the help of Dumbledore or another magical creature.
The businessman could be trying to revolutionize the wizarding education system from a business perspective. He sees potential in making Hogwarts more efficient and cost - effective. He proposes ideas like installing modern muggle - like technology for administrative purposes or outsourcing some non - magical aspects of the school's operations. This causes a stir among the Hogwarts staff and students. Another plotline could be that he is a muggle - born who made it big in the muggle business world and now wants to use his wealth and influence to improve the status of muggle - borns in the wizarding world. He funds projects and initiatives that aim to bridge the gap between muggles and wizards.