One possible plotline could be that Damon is tortured by a powerful witch as revenge for something he did in the past. Maybe he accidentally killed a member of the witch's coven. Another could be that he is tortured by a group of vampires who want to send a message to Stefan. They might use vervain and sunlight to torture him in creative ways.
Another plotline could be Jeremy learning more about Damon's past. This can lead to Jeremy having a better understanding of why Damon is the way he is. In one fanfic I read, Jeremy discovers some secrets from Damon's early days as a vampire and it changes their dynamic completely. Jeremy becomes more empathetic towards Damon and they form a stronger bond.
Love. It's often a reason. Maybe he's being tortured because someone wants to get back at him for hurting their loved one. For example, if he broke a girl's heart who has a powerful father or brother, they might torture him to avenge her pain.
In some fanfictions, Damon's werewolf bite might lead to a series of events that test his relationship with Elena. For example, Elena could be desperate to find a cure for him and in the process, they discover new secrets about the supernatural world that was previously unknown. The bite could also be a catalyst for Damon to face his inner demons and re - evaluate his actions throughout his long life.
Well, one common plotline is the exploration of different relationships that were not fully developed in the show. For example, some fanfictions focus on a deeper bond between Caroline and Bonnie. Another is the 'what if' scenarios, like what if Elena had chosen Damon right from the start? There are also fanfictions that introduce new supernatural elements to Mystic Falls, making the town even more dangerous and exciting.
One interesting fanfiction could be where Bonnie and Damon team up to fight a new, powerful dark magic that threatens Mystic Falls. They start off as reluctant allies but gradually develop a deeper understanding of each other.
One interesting story could be about Damon and Bonnie being forced to team up in a magical quest. They start off disliking each other but gradually develop a mutual respect as they face various challenges together.
One interesting fanfiction could be where Elena and Damon go on a journey to find a hidden vampire realm. In this story, they face numerous challenges together and their relationship deepens as they rely on each other for survival. It's full of adventure and romantic moments.
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.
One interesting scenario could be that Damon compels Elena to forget all the bad things that have happened between them. This would create a sort of fresh start for their relationship. They could then begin to build a new bond without the weight of past conflicts. For example, Elena might start to see Damon in a completely different light and they could explore a more positive side of their connection.
Another plotline could be about the power struggle among fallen vampires. Maybe some want to rise again to their former status, while others are content with their new, more subdued existence. This can lead to a lot of in - group drama and conflicts.