A common plotline is the sister's adjustment to the new world she's come back to. Things might have changed a lot since she died, like new vampire lords or different witch covens in control.
One popular fanfiction with this theme might be 'The Resurrected Sister's Revenge'. It delves into how the sister's resurrection changes the dynamics among the characters. She might have new powers or a different perspective on the vampire - human - witch world in Mystic Falls.
One common theme is loyalty. Sisters in the fanfiction often show unwavering loyalty to each other despite the supernatural challenges they face. Another is sacrifice. They might be willing to sacrifice their own happiness or safety for their sister. For example, in many stories, a sister will put herself in danger to protect her sibling from a vampire or a witch's curse.
In Vampire Diaries fanfiction, the concept of a twin sister sacrifice can add a whole new layer of drama. It could be related to some dark magic ritual where a twin's sacrifice is needed to gain power or break a curse. For example, perhaps a powerful vampire or witch demands it to achieve immortality or to control the supernatural elements in Mystic Falls.
One common theme is family loyalty. The sisters often have to stick together in the face of the many threats in the vampire - filled world. Another is power struggles. The sisters may have unique powers that others want to control or use for their own gains.
Love is also a common theme. It could be romantic love for her character or platonic love within the family. In some fanfictions, Klaus's sister falls in love with a character from the show, and this love story is intertwined with her relationship with Klaus. For instance, in 'Love and Blood', her love interest is a werewolf, which creates a lot of drama considering the vampire - werewolf dynamic in the Vampire Diaries.
One interesting fanfiction could be where the Gilbert sister discovers a hidden power within herself that links her to the vampire world in a unique way. Maybe she has the ability to see the true nature of vampires, even when they are using their compulsion. This could lead to all sorts of interesting plot twists as she gets involved with the main characters of the show.
One common theme is her struggle to fit into the world that has been turned upside down by the presence of vampires. She often has to deal with the danger that vampires pose to her and her loved ones while also trying to understand their complex nature.
You can also explore the impact on the relationships within the Vampire Diaries universe. Maybe the sister was in a relationship before the amnesia. Now, her partner has to deal with her not remembering their love. It could lead to some really interesting plot twists, like the partner having to fall in love with her all over again while she discovers new aspects of herself.
One possible plotline could be that Tatia's sister is a long - lost relative who suddenly shows up in Mystic Falls. She might have some hidden powers or knowledge about the vampire - werewolf - witch triangle that the main characters are unaware of, and this knowledge could either help or hinder them in their battles.