One frequent theme is the exploration of good and evil. Castiel represents the good side of angels, while Lucifer is the symbol of evil. Fanfics often play around with blurring these lines, showing that maybe Lucifer isn't all bad and Castiel isn't all good. Also, the theme of loyalty comes up a lot. Castiel is loyal to his cause, but his relationship with Lucifer makes him question that loyalty at times. This creates a lot of internal conflict for his character, which is very interesting to read about.
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.
Well, humor is also a common theme. Donna has a great sense of humor, and when combined with Castiel's often - literal and somewhat naive view of things, it creates some really funny situations. And of course, the overarching theme of fighting for good in the world full of evil is almost always present in 'castiel and donna fanfic'.
One common theme is loyalty. They are always there for each other in most fanfics, no matter what the situation is. Another theme is the struggle between the human and the supernatural world as Castiel is an angel and Dean is a human hunter.
One common theme is friendship. Since both Castiel and Cassiel are often portrayed as angels, their bond of friendship is a key aspect. Another theme is redemption. Many fanfics explore how they can redeem themselves for past actions.
Betrayal is also a theme. Sometimes he is betrayed by those he trusts, which causes great sadness. For example, when his fellow angels turn against him. And there's the theme of unrequited love. His feelings for certain characters may not be reciprocated, adding to his sorrow. This is often explored in 'castiel sad fanfic' to show the depth of his emotional turmoil.
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.
One common theme is power. Since Castiel is an alpha, his power is often explored, like how he uses it to protect or lead. Another theme is loyalty, as in how his pack or those around him are loyal to him, and vice versa.
Another theme is self - discovery. Castiel in these omega fanfics usually goes through a journey of understanding his own omega nature. He might discover new powers or abilities related to being an omega, or he might learn more about his place in the world. This can be really interesting as it gives a new dimension to the character that we might not see in the original source material.