Friendship is also a big theme. Harry and Castiel are from different universes, so the development of their friendship is often at the center of the stories. They have to overcome cultural and power - based differences to become friends, which makes for an interesting read.
Another theme is the discovery of new worlds. Harry is used to the wizarding world, and Castiel is from the celestial realm. Fanfics often explore what happens when they introduce each other to their respective worlds, like Harry showing Castiel the wonders of Hogwarts or Castiel taking Harry to see the heavens.
One common theme is Castiel's struggle with his angelic nature. He often has to balance his loyalty to heaven and his newfound connections with humans.
Another theme is self - loathing. In 'castiel depressed fanfic', he frequently blames himself for things that have happened, whether it's his actions in battles or his perceived failures in protecting others. This self - loathing is a big part of his depressive state.
The theme of self - discovery is also prevalent. As a female Castiel, she has to figure out her place in the world, both as an angel and as a female entity. This often involves her coming to terms with her new identity, learning about her powers in a different context, and finding her role in the fight against evil in a more female - centric way.
Reflection is also a big theme. Castiel has a long history, and on his birthday, he may look back on all the things he has been through, the people he has met, and the choices he has made. This can add a lot of depth to the fanfic and make readers understand his character better.
The theme of sacrifice also pops up a lot. Castiel may have to sacrifice his angelic duties or powers for his wife, or the wife might sacrifice her own safety or desires for Castiel. This creates a sense of drama and emotional depth in the stories. For instance, in one fanfic, the wife gives up her chance at a normal life to stay with Castiel in the dangerous world of angels and demons.
There can be a theme of spiritual discovery as well. In some fanfics, his blindness is seen as a way to connect more deeply with the spiritual realm. It can be a way to show that there are other ways to 'see' beyond physical sight, and it adds a really interesting layer to his character.
A common theme is the power struggle. Castiel is often seen as a more 'pure' angel, while Lucifer is the rebellious one. Their interactions are filled with this underlying battle for dominance or influence. Another theme is redemption. Sometimes Lucifer is portrayed as having a chance at redemption, with Castiel being a key factor in that.
The theme of protection is often present. Castiel, being an angel, has a natural inclination to protect. So in these fanfics, he not only babysits but also safeguards the children from various threats, whether they be physical or more supernatural in nature. For example, in some fics, he might protect the kids from demons while trying to make them eat their vegetables at the same time.
One common theme is the struggle between good and evil. Castiel is an angel, and Meg is a demon, so there's always that conflict. Another theme is redemption. Meg might be seen as someone who could be redeemed through her relationship with Castiel. And of course, love is a major theme. Their relationship, which is so unexpected, often leads to stories of love conquering differences.
Another theme is growth. In these fanfics, Castiel usually grows as a character. He might learn about human values like love, friendship, and loyalty in a more intimate way since he's part of a family. For instance, he could start to understand the concept of a family dinner and the significance of sharing time with loved ones.