One common theme is loyalty. Their loyalty to each other, whether it's in the face of danger or personal challenges, is often explored. For example, in many fanfics, they stand by each other no matter what.
Friendship is a very common theme. The stories often focus on how Castle and Vaughn support each other through different situations.
Sure. One great Beckett and Vaughn fanfic is 'The Unlikely Alliance'. It explores their relationship in a new and exciting way, with lots of action and emotional moments.
He could react with anger. After all, if he has feelings for Beckett, seeing her with someone else like Vaughn might make him furious. He might lash out at both Beckett and Vaughn without really understanding the situation.
Another thing that could occur is that Castle decides to confront Beckett about what he saw. He could be really straightforward and ask her what's going on between her and Vaughn. This could lead to an argument or a really honest conversation about their relationship.
A common theme is friendship. Many fanfics explore how Beckett and Alexis become friends and the bond they share. Another theme is growth, as they both develop as characters within the fan - created stories.
One common theme is family bonds. Since it's about a father - son relationship, many stories explore how they communicate, misunderstand, and then reconcile. For example, a story might show the son struggling to live up to the father's expectations at first, but then they grow closer as they understand each other better.
One common theme is friendship. Many fanfics start with them as friends and then explore how that relationship can evolve. Another theme is mutual understanding. Since they have different personalities, showing how they come to understand each other is popular.
One common theme is the struggle between the vampire nature and human morality. Beckett, as a vampire, often has to grapple with his blood - thirsty instincts while still holding on to some human values.
Friendship is also often explored. Maybe they start as acquaintances and gradually become really good friends. And there could be themes related to self - discovery. As they interact, they learn more about themselves. For example, Lily might discover a new side of herself because of Beckett's influence. There can also be some mystery - themed fanfics where they solve some kind of mystery together.
Love and acceptance is also a prevalent theme. Since Beckett comes into Castle's life and becomes part of Alexis's world, fanfics may focus on how they all learn to love and accept each other fully. This could involve storylines where there are initial misunderstandings but eventually they come to a place of complete acceptance and harmony in their relationships.