One way is to make it a spell or a curse in the Harry Potter world that somehow spreads to the Twilight world. For instance, a dark wizard creates the 'Love Me Dead' spell and it starts affecting the vampires and werewolves in Twilight, making them lose their ability to form normal relationships.
It could be incorporated as a new form of magic. Maybe a visiting wizard from a far - off land has this power and shares some of its secrets with Hogwarts students.
Well, it might be a very dark fanfiction. Since 'Love Me Dead' sounds rather gloomy. In the story, the magic from Harry Potter and the supernatural elements of Twilight could be combined in a twisted way. The characters could be constantly struggling between their normal feelings and this 'Love Me Dead' influence. Like Harry Potter might find his magic being affected by it and the Twilight vampires might find their thirst for blood changing because of it.
Humor can be added through character quirks. Like Neville's clumsiness can be exaggerated in a funny way. For instance, he could accidentally trip over his own plant while trying to show it off in Herbology class. Also, using puns related to magic. For example, when someone says 'I'm so charmed, it must be the spell of good humor!'
In Harry Potter fanfic, the red string of fate could be part of an ancient magic. Maybe it's related to the founders of Hogwarts. For example, if the red string links two students, it could be a sign that they are meant to revive an old magic together. In Twilight fanfic, it could be a supernatural element from a different culture. A vampire might discover that the red string of fate connects them to a human in a way that defies their natural instincts.
One way is through the wizarding economy. For example, the Weasley twins' joke shop, Weasleys' Wizard Wheezes. Fanfiction could expand on the business side of it, like how they manage inventory. They might have to source ingredients for their magical pranks from different wizarding markets. Another aspect could be marketing. How do they promote their products? They could use magical means like enchanted flyers that follow potential customers. Also, they need to deal with competition, perhaps from other prank - selling shops in Diagon Alley.
Another way is to have the kitten be a gift from a mysterious character. Maybe Dumbledore gives a kitten to Harry as a way to help him deal with the stress of fighting Voldemort. The kitten could have some sort of calming magic that helps Harry stay focused and centered during difficult times. This would add an interesting dynamic to their relationship and also give the story a new angle to explore.
One way is to have a crossover where the technology of transformers somehow enters the wizarding world. For example, perhaps a magical experiment gone wrong causes a transformer to appear in Hogwarts. The students might be both amazed and a bit scared at this mechanical being. It could also be that a wizard or witch discovers a way to use transformer parts to enhance their magic, like using a transformer's energy source to power a particularly large and complex spell.
One way a minotaur could be incorporated in Harry Potter fanfiction is as a new magical creature in the Forbidden Forest. It could be a guardian of some long - lost magic or a hidden area within the forest.
They can be incorporated by creating crossovers. For instance, a spell from Harry Potter could find its way into the Twilight world and Bella could be the one to encounter it. This would add an element of magic to the Twilight story that wasn't there before.
Well, in some Harry Potter fanfiction, Khajiit could be incorporated as new students at Hogwarts. Maybe they have their own unique magical abilities related to their Khajiit nature, like enhanced stealth or senses that could be used in magical tasks such as sneaking around the Forbidden Forest.