One way to merge the worlds is through a shared magical object. Imagine there is a magical stone that has the power to transport people between the two worlds. A character from the Harry Potter world discovers this stone and ends up in Jack's world. There, they find that the giants are being controlled by a dark magic that is similar to the Dark Arts in Harry Potter. So, they decide to use their combined knowledge to stop this dark force.
In fanfiction, the merge could happen due to a prophecy. A prophecy could state that only by combining the strength of the wizarding world (Harry Potter) and the courage of Jack the Giant Slayer's world can a great evil be defeated. This would bring characters together. For example, Hermione could use her vast knowledge of magic to figure out how to defeat the giants, while Jack could use his physical strength and knowledge of his world's terrain to lead the group. This would be a really interesting combination of different skills and cultures from the two worlds.
The worlds could merge through a magical portal. For instance, a wizard in the Harry Potter world accidentally creates a portal to the land of Jack the Giant Slayer while experimenting with a new spell. Then, characters from both sides start to interact. The wizards could teach the people in Jack's world about magic, and Jack could teach them about his skills in fighting giants.
One interesting concept could be a magical crossover where the giants in Jack the Giant Slayer are influenced by the magic from Harry Potter. For example, perhaps some giants have wands and can perform basic spells. Another idea is that Hogwarts students go on an adventure to the world of Jack the Giant Slayer as part of a special magical studies project. They could use their knowledge of magic to outwit the giants.
One way the worlds could merge is through a magical portal. Maybe a Hogwarts student accidentally discovers a portal that leads to the world of Princess Mononoke. The student could then introduce magic from the Harry Potter world to the people in Mononoke's world, like using spells to heal the forest spirits that are sick or injured. Another aspect could be the sharing of beliefs. The respect for nature in Princess Mononoke's world could influence the wizards in Harry Potter to be more in tune with the natural magic around them.
Authors often start by finding a connection point. For example, a magical portal could be the link between the Harry Potter world and Sesshomaru's world. This allows for the characters to meet in a somewhat believable way.
In some fanfictions, they merge through magical artifacts. For instance, the Sword in the Stone could be related to the Sword of Gryffindor. Maybe the two swords have a shared origin or power, and this connection brings the two worlds together. Characters from Harry Potter might be drawn to Camelot to discover more about this connection.
A great fanfiction idea could be a time - travel story. Jack is sent back in time to when the first giant - human war started. He uses his knowledge from his own time to try and change the course of history and prevent the destruction that led to the situation in the original story. He could also meet his ancestors and learn about secrets that were long forgotten in his own time.
The characters often fit into common fantasy archetypes. Harry is the hero on a quest, much like in many traditional tales. The story also uses common settings like a castle for Hogwarts. These are elements that are often used in fanfiction, where authors take well - known settings and character types and put their own story within them.
Jack himself is obviously a very popular character to include. He's the hero of the story, so most fanfictions would center around him in some way. The princess is also a popular choice. Writers can explore her relationship with Jack further, like how she helps him in battles or how their relationship develops after the main events of the story. And of course, the giants can be great characters to include. You can create different personalities for them, like a giant who is more intelligent and cunning than the others.
In 'Jack and the Giant Slayer', Jack is a young farm boy. One day, he exchanges the family cow for some magic beans. These beans grow into a huge beanstalk that reaches the sky. Jack climbs the beanstalk and discovers a land in the sky inhabited by giants. The giants are cruel and have been stealing things from the human world. Jack manages to steal some of their treasures, like a magic harp that plays by itself and some golden eggs. But the giants notice and chase him. Jack bravely fights them and eventually cuts down the beanstalk, killing the giants and saving his village.
Another way is through a powerful artifact. Suppose there is an ancient artifact in Highschool DxD that has the power to connect different dimensions. When it is activated, it links to the world of Overlord. This could lead to all sorts of storylines, like characters from both sides trying to control the artifact for their own purposes, or working together to keep it from falling into the wrong hands.
In many Harry Potter fanfictions, half - giants are often portrayed as having great physical strength, just like Hagrid in the original series. They might be shown as having a gentle heart beneath their tough exterior. For example, some fanfictions might explore a half - giant character's struggle to fit into the wizarding world due to their large size and different nature.