One possible plot could be that the pregnancy is a result of some sort of magical or otherworldly event. Castiel might feel a strong sense of responsibility to protect Meg and the unborn child. He could use his angelic powers to keep them safe from various threats in the Supernatural universe, like demons or other malevolent forces.
Yes, there could be. Fanfiction writers are known for their creativity and often come up with all sorts of scenarios. But it's important to note that this might be a very niche and perhaps controversial concept within the fan community. Since Castiel and Meg have a complex relationship in the original source material, some fans might be interested in exploring this extreme scenario in fanfiction.
I really like 'A Meeting of Opposites'. In this fanfiction, the author explores the idea of Castiel and Meg having to work together on a mission. It's a great read because it plays with their personalities. Castiel's naivete and Meg's cunning are both highlighted and as they interact, it creates a lot of tension and some really cool plot twists.
Character development is crucial. In fanfiction, we get to see different sides of Meg and Castiel. Maybe we see a more vulnerable side of Castiel or a less evil - more complex side of Meg. And the plot usually revolves around some sort of conflict, either between them or against a common foe.
One popular 'Meg and Castiel fanfiction' story is 'The Unlikely Bond'. In it, Meg and Castiel are forced to work together against a common enemy, which leads to a slow - building understanding and an unexpected connection between them. Another is 'Meg's Redemption' where Meg tries to find a way to redeem herself in Castiel's eyes. It delves deep into her character's struggle and how Castiel plays a part in her journey.
You can try Tumblr as well. There are many fanfiction writers who post their 'Meg and Castiel' stories on their blogs. Just search for relevant tags such as 'MegxCastiel fanfiction' or 'Meg and Castiel fic'. Wattpad is another platform where you might find some good stories. However, the quality can vary more on Wattpad compared to the other two, but it's still worth a look.
The fanfiction might show Meg dealing with the physical and emotional changes of pregnancy while still being her tough self. She might have to fight off those who would try to harm her because of the baby. Castiel, on the other hand, would be by her side, using his powers when necessary. It could be a story of their growth as individuals and as a couple.
Another popular theme is the power struggle between them. Meg is a powerful demon and Castiel is an angel with his own set of powers. Fanfictions sometimes focus on how they use their powers against each other, or in some cases, how they learn to combine their powers for a common goal, which makes for some really exciting action - packed stories.
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.
I really liked 'In the Shadows with Meg and Castiel'. It's a more introspective piece that explores their individual struggles and how they come to rely on each other. The descriptions in the fanfiction are really vivid, making you feel like you're right there in the Supernatural universe with them.