One popular trope is the 'enemies to lovers' scenario. For example, a vampire and a hunter might start off hating each other but gradually fall in love. Another common one is the 'soulmate' trope, where two characters are fated to be together. And of course, there's the 'redemption' trope, where a character who has done bad things tries to make up for it.
The 'time - travel' trope is also quite popular in 'The Vampire Diaries' fanfiction. Characters might go back in time to change events, or they might be from a different time period and have to adjust to the modern world of the show. There's also the 'alternate universe' trope, where the story takes place in a different version of the 'Vampire Diaries' world, like a world where vampires are the rulers or where magic doesn't exist.
One popular trope is the 'enemies to lovers' scenario. In both Charmed and Vampire Diaries, there are characters with opposing views or allegiances that fans like to pair up romantically. For example, in Vampire Diaries, a fanfiction might explore the relationship between a vampire and a vampire hunter who start off hating each other but gradually fall in love. Another trope is the 'alternate universe' where the story takes place in a completely different world from the original shows, like a world where the witches in Charmed have different powers or the vampires in Vampire Diaries don't have to feed on blood. And the 'time - travel' trope is also common, where characters go back in time to change events in the shows' histories.
One popular trope is the crossover aspect itself. Writers often like to bring the characters from Spider Man and Vampire Diaries together in unexpected ways. For example, having Spider Man face off against the vampires in Mystic Falls. Another is the 'fish out of water' trope, like if Peter Parker somehow ended up in the Vampire Diaries' universe and had to adapt to its rules.
One popular trope could be the 'outsider' trope. Pearl and Jonathan might be seen as outsiders in the vampire community, and the fanfiction could revolve around them trying to find their place. Another is the 'redemption' trope, where they might have done something wrong in the past and are now seeking redemption.
The 'time - travel' trope can be seen in some fanfictions. A character from 'Vampire Diaries' might travel back in time to the era of 'Merlin' and change the course of events. Or vice versa. The 'hidden identity' trope is also popular. A character might be hiding their true identity as a wizard from 'Merlin' in the 'Vampire Diaries' world. And the 'battle of powers' trope, where characters from both series test their powers against each other to see who is stronger.
One popular trope is the powerful Mikaelson sister. In many fanfictions, she's often depicted as having unique powers that even her brothers might envy. For example, she could have the power to control time, which adds an interesting dynamic to the story. Another trope is the love triangle. Maybe she's caught between a vampire from another clan and a werewolf, creating a lot of drama and tension.
You can start by looking on fanfiction websites like Archive of Our Own (AO3) or FanFiction.net. These platforms have a large collection of 'The Vampire Diaries' fanfiction. Just search for 'The Vampire Diaries' on the site and then browse through the stories to find the ones that might be what you 'all need'.
The 'Forbidden Love' trope is also common. Kai might fall in love with a character he shouldn't, like a vampire hunter or a witch from an opposing coven. It creates a lot of drama and tension in the story. For instance, in some fanfictions, Kai's love interest is from a family that has been sworn enemies of his for generations, and they have to fight against all odds to be together.
One of the most popular tropes is the 'forbidden love' trope. Since Stefan has a complex past and Caroline has her own set of responsibilities in the vampire world, their relationship can often be seen as something that's not supposed to happen. It adds a lot of drama and tension to the stories.
The 'power - sharing' trope is also common. This could be where Hermione's magic and the powers of the vampires or other supernatural beings in The Vampire Diaries interact in unexpected ways. Maybe she uses her magic to enhance their powers or vice versa. It creates a lot of interesting plot possibilities.
One popular trope is the 'fix - it' where characters go back in time to change a tragic event. For example, in many fanfictions, a character might go back to prevent the death of a loved one like Jeremy. Another common trope is the 'fish - out - of - water' situation. When a character travels back in time, they have to adapt to the different time period, like different social norms and fashion. This can lead to some really funny and interesting situations.