One idea could be a story where the Addams family moves to Forks. Wednesday Addams could befriend Bella, and they end up getting into all sorts of strange adventures together. Maybe Wednesday helps Bella deal with the vampires and werewolves in her own unique, macabre way.
A plot could involve the Volturi from Twilight coming to the Addams family's town. The Addams family, not ones to be intimidated, stand up to them. Gomez and Morticia show the Volturi that their family has its own set of rules and powers that are not to be trifled with.
Morticia could be a vampire in this fanfiction mash - up. Her alluring and mysterious nature would fit right in with the Twilight vampires. She could have her own coven, separate from the Cullens, and perhaps there would be a rivalry or an alliance formed between them based on her interactions with Carlisle. She would bring her own sense of style and elegance to the vampire world, along with the Addams family's penchant for the macabre.
You can start by finding common traits. For example, both worlds have characters that are outsiders in a way. The Cullens in Twilight are different from normal humans because they are vampires, and the Addams family is different from the average family with their love for all things dark and spooky. So, you could have a situation where they recognize this similarity in each other.
The Addams family could fit into the wizarding world by bringing their own sense of style and values. Their mansion could be a place where students go for a different kind of magical experience. They might hold parties where they showcase their strange magical artifacts. In terms of the Hogwarts houses, they might not fit the typical mold. Wednesday could be a unique Slytherin who doesn't care about the pure - blood - mania but rather about her own personal power. Pugsley could be a Hufflepuff who is loyal to his family's odd ways. And the family as a whole could contribute to the diversity of the wizarding world.
Morticia would likely be intrigued by Harry. She might be drawn to his mysterious past in the wizarding world and his magical abilities. Gomez, on the other hand, would probably be excited to have a new family member to share his adventures with. Wednesday might see Harry as an interesting addition, someone who could bring a different kind of darkness to the family. And Pugsley might look up to Harry, especially if Harry shows him some cool magic tricks.
Perhaps Harry is a new neighbor in the Addams Family's neighborhood in the fanfiction. He starts off as an outsider but gradually gets drawn into their strange world. He could be intrigued by their unique lifestyle and they, in turn, might be interested in his different perspective. He could end up becoming a part of their family - like circle, joining in on their unusual family activities such as séances or midnight picnics in the cemetery.
One idea could be that the Addams family visits Hogwarts. Wednesday could be intrigued by the Dark Arts classes and start causing some spooky chaos among the students. She might even try to out - do Draco Malfoy in being menacing.
The Addams Family could fit into Gotham's universe in many ways. For example, they could be seen as an eccentric family living on the outskirts of Gotham. Their macabre interests and strange behavior might be misinterpreted by the citizens of Gotham as something more sinister. Gomez could interact with some of Gotham's mobsters in a very unique way, perhaps out - of - the - box business deals. Morticia's elegance and mystery would add a different kind of charm to the dark city. And Wednesday, with her penchant for the morbid, could find Gotham a rather interesting place to explore, especially with all the dark alleys and strange characters.