Well, Harry Potter is from a world of magic, wizards, and Hogwarts, while Goku is a Saiyan from the Dragon Ball universe with superhuman strength and the ability to fly. If they were to interact, it would be quite a sight. Harry could use his magic spells, like Expelliarmus to disarm Goku, but Goku's speed and power might make it hard for Harry to land a hit. Goku, on the other hand, might be intrigued by Harry's magic. He'd probably want to learn about it or test his strength against it. Maybe they could team up to fight a common enemy, with Goku using his physical power and Harry using his strategic spells.
I think their interaction would start with a lot of confusion. Goku has no concept of magic in his world, and Harry would be equally baffled by Goku's ki energy. However, they both have a strong sense of justice. So, once they got over the initial shock, they would probably find common ground in protecting the innocent. Harry could use his invisibility cloak to sneak up on enemies, and Goku could provide the brute force in battles. Their combined skills could be a formidable force against any foe.
In a fanfiction scenario, Harry Potter and Goku's meeting could be epic. Goku's carefree and adventurous nature might contrast with Harry's more serious and burdened personality. But they could learn from each other. Goku could teach Harry about the importance of physical training and pushing one's limits. Harry could introduce Goku to the wonders of magic, like the Room of Requirement where one can get whatever they need. They might also have some friendly competitions, like a race where Goku uses his flight and Harry uses his broomstick, or a duel where Goku tries to dodge Harry's spells with his speed.
Well, it could be really interesting. Harry would probably grow up with a very different set of values. Goku is all about strength and protecting the Earth in a very physical way. Harry might learn martial arts instead of magic at first. He could be more straightforward in dealing with his enemies, using punches rather than spells. And his idea of friendship might be more like Goku's, based on mutual respect for power and a shared goal of protecting those in need.
In a more psychological sense, Harry might initially be afraid of Freddy because of his appearance and the way he operates in dreams. However, as he gets to know more about this strange entity, he could start to pity Freddy in a way. He might realize that Freddy is also a victim of some dark magic gone wrong in his own world. And this realization could lead to Harry trying to find a way to either banish Freddy back to his own realm or even cure him, if possible.
Their interaction could be quite interesting. Goku might be curious about Android 21's abilities, always eager to test his own strength against hers. Android 21 could be initially guarded but gradually open up to Goku's friendly and straightforward nature.
In a fanfiction, a Harry Potter and a Khal interaction could be full of misunderstandings at first. Harry's use of a wand and strange words for magic would seem very odd to the Khal. But as they get to know each other, they might find common ground in their leadership skills. Harry has led his friends in many dangerous situations in the wizarding world, and the Khal is a natural leader among his people. They could exchange ideas on how to lead and protect their respective groups.
Well, in such a fanfiction, Harry Potter would probably gain some amazing physical abilities from Goku's training. He might be able to move at super - fast speeds and have enhanced strength. His magical skills could also be combined with Goku - like combat techniques, making him an even more formidable wizard in battles against Voldemort or other dark forces.
They could learn a great deal from each other. Harry could teach Optimus about the different kinds of magic, like the Patronus charm which is used to fight off Dementors. Optimus, on the other hand, could show Harry the value of technology and teamwork within the Autobot ranks. Their combined forces could be a great asset in a fight. If they were facing a common enemy, say a new dark wizard who has also allied with the Decepticons, they could use both magic and advanced weaponry to take them down.
Goku and Grandpa Gohan's interaction could be full of wisdom - sharing. Grandpa Gohan was a wise man, and he would pass on more of his knowledge to Goku. Goku, in turn, would tell Grandpa Gohan about all the new friends he has made and the different planets he has visited. They might also spar a bit, just like in the old days, with Grandpa Gohan giving Goku some pointers.
Their interaction might become more intense. Goku, being the experienced fighter, could start to teach Caulifla some really advanced techniques, and Caulifla would be eager to learn. This could lead to some really exciting training scenes between them.
Well, the plot could start with Goku somehow ending up in the Harry Potter universe. Maybe through some kind of interdimensional portal. He meets Harry's mother and falls in love. Then, Harry is born with some unique powers that are a combination of Goku's Saiyan abilities and the magic of the wizarding world. As Harry grows up, Goku tries to teach him about his Saiyan heritage while also dealing with the challenges of the wizarding world like Voldemort.
It could be a really wild and interesting story. Maybe Goku Black could end up at Hogwarts somehow. He might use his power to either cause chaos or try to take over the wizarding world. And the wizards would have to use their magic in ways they've never thought of to fight him.