Bonnie would be an interesting match. Bonnie is a powerful witch, and as Silas' daughter would likely have some sort of magical abilities too. They could team up to fight against common enemies or to solve some of the magical conundrums in Mystic Falls. Their relationship could be a bit rocky at first, as Bonnie might be cautious about getting involved with Silas' family, but over time they could develop a deep bond based on respect for each other's powers.
It's hard to say who the 'best' Silas is as it depends on personal preference. Some might like a more sympathetic portrayal of him, where he has redeeming qualities. Others might prefer a really menacing and powerful version that stays true to his villainous nature in the show.
One interesting plot could be her trying to break the curse her father is under. Since Silas has been trapped in a sort of limbo for so long, his daughter might feel a strong urge to free him. She could start by seeking out the powerful witches in Mystic Falls and trying to learn about the magic that was used to imprison him. Another plot could be her falling in love with one of the main characters, like Stefan or Damon. This would create a lot of drama as she has to balance her love for them with her loyalty to her father.
Another interesting pairing could be Jeremy and Caroline. Caroline is already a vampire, so she could mentor Jeremy in a way. They could have a fun, flirty relationship where they go on adventures together and learn more about the vampire world as a team. It would be interesting to see how their personalities clash and mesh at the same time.
One interesting aspect in Silas - related Vampire Diaries fanfiction could be his relationship with other characters. For example, how he might interact with Elena or Damon in alternate scenarios. Maybe he uses his powers in different ways than in the show.
In many fanfictions, Silas's character may develop from being a purely power - hungry villain. He might start to show more vulnerability when it comes to Amara. For example, he could sacrifice some of his power - seeking plans just to keep her safe.
There might be a fanfiction where Silas tries to break the curse on Amara in a different way. He travels through different dimensions to find a solution, and along the way, they face many challenges together that test their relationship. This would add a lot of adventure and mystery to their story.
Damon Salvatore would also be a good choice. His dark and brooding nature could contrast with Mary Louise and Nora's personalities. There could be a lot of tension and unexpected alliances or rivalries in a fanfiction where they are all involved.
Klaus Mikaelson is often paired with the Salvatore sister in fanfiction. His complex character and the power dynamics between them can lead to some really engaging storylines. Elijah Mikaelson is also a popular choice. His noble and protective nature can be a great contrast to the Salvatore sister's more fiery or independent personality. Tyler Lockwood might also be a good pairing, especially if the fanfiction focuses on the werewolf - vampire dynamic in the Vampire Diaries universe.
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.
I think Harry and Damon would be an interesting pair. Harry has his strong sense of justice and Damon is this complex, morally grey vampire. Their interactions would be full of tension and banter. They could learn from each other - Harry about the vampire world's darker side and Damon about the power of friendship like Harry has with his friends. Another great pair could be Hermione and Bonnie. Both are smart and powerful in their own ways. They could combine their magic knowledge to solve problems that come up in the crossover.