Family is a very common theme. Since she's part of the Winchester family, stories often revolve around her relationship with her brothers and how they protect each other.
Well, identity is a significant theme. The Winchester sister often has to figure out who she is in relation to her family and the hunting world. Also, sacrifice is common. She may have to sacrifice her own desires or safety for the greater good of her family or to save the world from supernatural threats. There's also the theme of friendship as she might make friends with other hunters or people in the supernatural world.
Well, the theme of protection is quite prevalent. The sister might be in a position where she needs to protect her brothers or vice versa. Also, there's the theme of identity. She could be trying to figure out who she is in relation to the Winchester legacy. For example, is she just a hunter like her brothers or does she have a different role? And then there's the theme of sacrifice. There are times when the sister has to make sacrifices for the greater good of the family or the world in these stories.
The theme of the baby having some sort of special or mysterious quality also pops up a lot. This gives an interesting twist to the story, as the characters have to deal with not only a baby but also the implications of this special quality, whether it's a connection to the supernatural world or some other extraordinary ability.
Well, identity is a major theme. Bella has to figure out who she is now as a Winchester sister. There's also the theme of power. She might gain new powers or abilities in this new setting, or learn to use her existing ones in different ways. And of course, there's the theme of love and loyalty, not just within the family but also towards the cause of fighting the bad guys.
Family dynamics is also a big theme. How does Sam react to being an uncle? How does Castiel fit into this new family situation? And of course, how does Dean interact with the mother of the baby, if she's in the picture? These are all aspects of family dynamics that are explored.
One common theme is protection. Dean, being a hunter, often has to protect the baby girl from various supernatural threats. Another theme is family. The baby girl becomes a part of Dean's makeshift family, and it shows how he adapts to having this new family member. And love, of course. Dean grows to love the baby girl deeply, which is a central part of these stories.
Family is a very common theme. Since Dean comes from a complex family situation, fanfics often explore his relationship with his father and brother at a young age.
A theme that is sometimes explored is the baby daughter's connection to the supernatural world in a unique way. Maybe she has some sort of special ability or a link to the other side. This theme adds an element of mystery and adventure to the fanfictions. It also makes the story different from normal family - centric stories as it has that supernatural twist.
One common theme is family protection. The little sister is often in need of protection from the various supernatural threats, and Sam and Dean are always there to save her. For example, in some fics, she might be targeted by demons because of her connection to the Winchesters.
One common theme is female empowerment. Many of these fanfictions feature female characters who are strong, independent, and capable of holding their own against the supernatural threats that the Winchesters usually face. For example, they might be skilled hunters or have special powers.