A mentor - mentee relationship could develop. The Winchesters, with their years of experience in fighting all kinds of supernatural beings, could mentor Harry. They could give him tips on combat strategies, survival skills, etc. Harry, on the other hand, could learn a great deal from them and maybe even apply some of those skills in his own world.
They might develop a friendship. Harry could see Daphne's kindness beneath her Slytherin exterior at the Yule Ball, and Daphne could realize that Harry is not just the 'Chosen One' but also a normal boy with normal feelings. This new understanding could lead to a friendship where they support each other through the challenges at Hogwarts.
After the war, they might travel around the wizarding world. They visit different magical communities and learn about new spells and cultures. Along the way, they rely on each other for support and protection. Harry, with his fame, sometimes faces challenges from those who still idolize or fear him, and Ginny is always there to stand by his side. Their adventures together make their relationship more solid and full of love.
In a fanfiction, their relationship might start off rocky. Deadpool's crazy antics would likely put Peter off at first. But as they face challenges together, they could grow to respect each other. Deadpool might learn some sense of responsibility from Peter, and Peter could loosen up a bit thanks to Deadpool's carefree attitude. Eventually, they could become a great superhero duo, with Deadpool providing the comedic relief and Peter the moral compass.
At first, it's likely to be tense. Harry has years of seeing Snape as a bully. But as they start living together, they begin to understand each other. Snape might show his more vulnerable side to Harry, like his memories of Harry's mother. Harry, in turn, starts to respect Snape's knowledge and sacrifice. Eventually, they develop a bond like a father - son relationship.
Well, at first, Harry might feel a bit out of place, but the Weasleys' warm welcome would soon make him feel at home. He would start to participate in their family discussions, offer his own opinions, and be a part of their decision - making processes. The Weasleys would teach Harry things that he missed out on growing up without a proper family, like how to handle family disputes in a healthy way. Harry, on the other hand, would bring his own unique perspective to the family. His fame and the things he had been through would make the Weasleys see the world in a different way. This exchange of ideas and experiences would continuously deepen their relationship over time.
One possibility is that they form an unlikely alliance. Maybe they start sharing their different skills and knowledge. For example, the Winchesters could teach Harry about hunting supernatural creatures in their way, while Harry could introduce some of his magic to them. They might also compare their experiences of facing great evils. The Winchesters have fought demons and angels gone bad, and Harry has battled Voldemort and his Death Eaters. It could be really interesting to see how they react to each other's stories.
They could become even closer friends. After going through the war together, they have a deep bond. Maybe they start to rely on each other more than ever, sharing every little detail of their lives.
They could develop a mentorship - like relationship. Lois, with her knowledge of the superhero world and her experience in dealing with complex personalities, could guide Conner. He, in turn, could offer her a fresh perspective on the world of superpowers.
They could develop a mentor - mentee relationship. The future Tsuna has more experience and knowledge, so he can guide the present Tsuna.
They could become very close friends. After the war, they both have a shared understanding of the trauma and changes they've been through. They might support each other in rebuilding their lives at Hogwarts or in the wizarding world in general.