I'm not entirely sure if there is a specific fanfic where Castle sees Vaughn kiss Kate. However, in the world of fanfic, anything can happen. Fanfic writers are very creative and they can come up with all kinds of scenarios that deviate from the original storyline. If such a situation exists in a fanfic, it could add a new layer of complexity to the relationships between the characters. It might even change the way we view the dynamic between Castle, Vaughn, and Kate.
Yes, it might be a plot point in some fanfic. Fanfic often takes existing characters and creates various scenarios, so it's quite possible that in a particular Castle - related fanfic, Castle could witness Vaughn kissing Kate.
Well, it depends on the specific fanfic. There are countless fanfics out there, and while some might include this scenario of Castle seeing Vaughn kiss Kate, others may not. It could be a really interesting and dramatic plot twist if it does occur in a fanfic. Writers like to play around with different character interactions to create unique stories. For example, it could lead to a whole series of events like Castle getting jealous or having a misunderstanding with Kate.
One implication could be that Castle might become jealous. This could lead to some tension between him and Kate.
Your best bet would be to search on large fanfic platforms. Archive of Our Own (AO3) is a great place to start. Just go to the website, type in 'Castle' in the search bar, and then add keywords like 'Vaughn', 'Beckett', and'seeing a kiss'. Another option is Fanfiction.net. Navigate to the 'Castle' section and use the same kind of keyword search. There may also be some smaller, more specialized fanfic sites related to the show, but AO3 and Fanfiction.net usually have a wide range of content.
It's possible that there are fanfics like that out there. The 'Castle' series had a lot of complex relationships, and fans often create fanfics to explore different 'what - if' situations. But I haven't come across one myself that has Castle seeing Vaughn kiss Beckett. You might have to dig deep into the fanfic archives or ask in dedicated 'Castle' fan groups on social media platforms.
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.
Friendship is a very common theme. The stories often focus on how Castle and Vaughn support each other through different situations.
He becomes more withdrawn. Normally Castle is quite social and outgoing, but with Kate gone, he loses his spark. He may stop joking around as much and become more serious.
Well, 'Castle and Vaughn: A New Beginning' is another great one. It starts with a fresh take on their relationship, perhaps in a different time or place. The story is full of twists and turns that keep you engaged. It has a lot of character development and the plot is quite engaging.
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.
You can try searching on fanfiction platforms like Archive of Our Own or FanFiction.net. These sites often have a wide variety of fan - created works, so there's a good chance you'll find something related to Castle Eric Vaughn there.
I'm not sure specifically as there could be many different interpretations. It might be a fan - created story where a character named Castle believes that Kate is cheating in the context of their relationship within the fan - created scenario.