Well, if you're doing a crossover with 'Buffy the Vampire Slayer', Buffy herself would be a great addition. Her slayer skills would create an interesting dynamic with the vampires from 'Interview with a Vampire'. Also, Angel from 'Buffy' could be included as he has a similar vampire - with - a - soul situation. Another good character could be Van Helsing from the various Van Helsing stories. His vampire - hunting skills would bring a lot of action to the crossover.
One idea could be a crossover with a supernatural detective series. The vampire from 'Interview with a Vampire' could team up with the detective to solve a series of murders that seem to be vampire - related but have a more complex, otherworldly origin. Another plot could involve a crossover with a fantasy world. The vampire enters a realm full of magic and strange creatures, and has to navigate this new world while dealing with his own vampiric nature. Maybe he meets a powerful wizard who wants to use his vampiric powers for some grand scheme.
It expands it by delving deeper into Armand's powers. For instance, in some fanfictions, we might see more about his ability to control minds on a large scale. This goes beyond what was shown in the original work and adds to the overall vampire mythology.
One common theme is self - discovery. Daniel, as a newly turned vampire, has to figure out who he is now. For example, in many fanfictions, he struggles with his new identity and the powers that come with it.
Some fanfictions also focus on the relationships between vampires from different regions. They might create new vampire clans and explore how they interact with the known characters from the original story. This can introduce new power dynamics and cultural elements within the vampire world.
Louis is also quite popular. His brooding and introspective nature gives a lot of room for character development in fanfiction. Many fanfictions might put him in different situations to see how he reacts, or they might explore his relationships in new ways, such as a different kind of friendship with Armand.
One interesting plot could be a different origin story for the vampires. Maybe they were created not just by a single vampire but a group of ancient beings. Another plot could be a love story between a human and a vampire that defies the normal rules of their relationship in the original story. And perhaps a plot where vampires are trying to co - exist with humans in a more open way.
Lestat is often a very popular character. His charm and his complex personality make him a great subject for fanfiction. Louis is also popular as he is one of the main characters in the original story and has a lot of room for further exploration in fanfiction. Claudia can be a popular character too, especially when writers explore her relationship with Louis and Lestat from different angles.
One interesting idea could be exploring the backstories of the minor characters more deeply. In the fanfiction, they might give a detailed account of how a particular vampire was turned and what their life was like before. Another idea could be alternative relationships between the characters. For example, a fanfic might explore a different kind of bond between Louis and Lestat that wasn't fully shown in the show.
Louis and Lestat are likely to be very popular. They are the central characters in the original work, and in fanfiction, people would love to explore their relationship further. Writers might delve into their complex feelings for each other, be it love, hate, or a mixture of both.