Well, it depends on what you consider 'good'. There are many 'Katherine's Daughter' fanfictions out there. Some focus on the daughter inheriting Katherine's cunning and manipulative traits while others take a different route and make her a more benevolent character in the otherwise dark Vampire Diaries world. It's really a matter of personal taste when it comes to finding a good one.
Elena is often portrayed as the more innocent and selfless one in fanfiction. She usually acts out of love for her friends and family. Katherine, on the other hand, is more self - serving. For example, in many stories, Elena will sacrifice herself for others, while Katherine will look for ways to save herself first.
One great fanfiction is 'The Doppelganger Dilemma'. It delves deep into the complex relationship between Elena and Katherine. It shows how their different personalities and experiences as doppelgangers create a unique dynamic. The story has some really interesting twists where Elena starts to understand Katherine's actions more, and Katherine, in a strange way, starts to protect Elena.
One common theme is the struggle with identity. Since she's Katherine's daughter, she has to deal with the reputation and legacy her mother left behind. Another theme is love and relationships, just like in the original show, exploring who she falls in love with among the existing characters.
There are fanfictions where Katherine returns from the dead in a different form, perhaps as a spirit. Damon, who has always had a deep connection with her, has to figure out how to interact with this new version of Katherine. It could involve a journey of self - discovery for Damon as he realizes that his feelings for her are more complex than he thought, even in this new and strange situation.
Katherine herself is also a great character in fanfiction. Her devious and manipulative ways add a lot of drama. In some fanfictions, her backstory is delved into more deeply, showing how she became the way she is. This can make her a more sympathetic or even more despicable character, depending on the writer's take.
Another type of fanfiction could be a time - travel one. Stefan and Katherine are sent back in time to a period before Katherine was turned into a vampire. In this time, Stefan tries to prevent Katherine from becoming a vampire in the first place. This would change the whole course of their relationship and the events in the Vampire Diaries universe. It would be full of interesting twists as they navigate through the past, trying not to change too much but also trying to change their own fates.
You can start by looking on popular fanfiction websites like Archive of Our Own (AO3). It has a large collection of fanfictions, and you can easily search for Vampire Diaries stories specifically about Stefan and Katherine. Just type in their names in the search bar, and you'll get a list of relevant stories.
The Vampire Diaries:
The Vampire Diaries Season 1
The Vampire Diaries Season 2
The Vampire Diaries Season 3
The Vampire Diaries Season 4
The Vampire Diaries Season 5
The Vampire Diaries Season 6
The Vampire Diaries Season 7
The Vampire Diaries Season 8
The Vampire Diaries Season 9
10. The Vampire Diaries Season 1 to Season 9, Subtitled Version