The early 2000s saw the rise of vampire-themed shows, but many of them ended up having similar storylines. One example is the presence of original vampires. Klaus Mikaelson in The Vampire Diaries becomes the main antagonist and love interest for Caroline, while in Buffy the Vampire Slayer, Buffy encounters vampire ancestors with whom she has a hostile relationship.
Another recurring theme is the death of the main character's parents. In The Vampire Diaries, Elena's parents die in a car accident, while in True Blood, Sookie Stackhouse's parents drown during a flood.
Both shows also explore the idea of a cure for vampirism.
The Civil War era is another common backdrop for vampire transformation. In The Vampire Diaries, Katherine seduces the Salvatore brothers and turns them into vampires, while in True Blood, Bill Compton undergoes the same process.
Finally, the death of a mother from cancer is another shared element. In The Vampire Diaries, Caroline's mother dies from cancer without a chance for a final goodbye, just like Buffy's mother Joyce in Buffy the Vampire Slayer.
These similarities between vampire shows in the early 2000s may have been coincidences or deliberate choices. However, they show that even the best vampire show was not as unique as it may have seemed.