A possible theme is the idea of taking risks. Since the love came without warning, the characters may have to take risks in order to pursue it. And there could also be a theme related to the exploration of new relationships. This unexpected love might lead to the characters exploring different aspects of relationships that they hadn't considered before in the context of the Castle fanfic.
There could be a theme of self - discovery. Through this unexpected love, the characters might learn new things about themselves, like their capacity for deep emotions. Also, the theme of vulnerability could be present. Falling in love suddenly makes the characters more exposed and open to getting hurt.
Well, in a Castle fanfic with 'love that came without warning', it might explore different character dynamics. For example, it could be a love between Castle and Beckett that catches them off - guard. This could lead to new storylines where they have to deal with their feelings while still solving crimes. It might also introduce some conflicts, like how their professional relationship is affected by this sudden love.
Survival could also be a theme. Given that Castle Rock has a somewhat dark and dangerous atmosphere, the kid may have to fight to stay alive. This could involve dealing with supernatural threats or dangerous people. Additionally, the theme of friendship might be present. The kid could form bonds with other characters in the town, and these relationships could help them navigate the difficulties they face.
The themes in the 'black sheep castle story' could be quite diverse. For instance, the theme of prejudice might be present. Just because someone or something is considered the 'black sheep', they might be wrongly judged by the others in the castle. Another theme could be change. The presence of the 'black sheep' could bring about changes in the castle, whether it's changes in relationships, power dynamics, or the overall atmosphere. Additionally, the theme of self - discovery might be there. If the 'black sheep' is a person, they might go through a journey of self - discovery within the context of the castle.
One possible theme could be celebration. Since it's set during the 12 days of Christmas in a castle, there would likely be a lot of feasting, singing, and general merriment.
One possible plotline could be that the baby has some sort of special ability or is in some way connected to a mystery they have to solve. Maybe the baby's birth coincides with a strange series of events in the city, and Castle and Beckett have to use their skills to protect the baby and figure out what's going on.
One possible plot is that Kate is in danger during an undercover operation. Castle, using his connections, gets wind of it and races to the scene. He manages to get her out just in time.
Maybe they stumble upon a government conspiracy. The government wants to keep something hidden and they are seen as a threat, so they are made to disappear. It could also be related to a scientific experiment gone wrong. They are in the wrong place at the wrong time and get caught in an energy field that transports them to an unknown location, causing them to disappear from their normal world.
One common theme is sacrifice. The characters are often willing to sacrifice a great deal for their love, showing that their love truly has no limits.
One possible theme could be a comical take on Batman in a baby - like or vulnerable state. It might be about how the other characters in the Batman universe react to this strange situation.