One common theme is the clash of different kinds of supernatural or otherworldly elements. Since 'Supernatural' has a lot of demons, angels, and ghosts, and 'Torchwood' deals with aliens and time - space anomalies, when they cross over, there's often a struggle to understand and combat these different threats. For example, in many fanfics, the characters have to figure out how to fight an alien - possessed demon or something similar.
Another theme is the exploration of different character dynamics. The Winchester brothers from 'Supernatural' have a very different relationship compared to the members of the Torchwood team. In crossover fanfics, we often see how they interact, whether it's through trust - building or initial mistrust. For instance, Sam might be initially suspicious of Captain Jack's motives, and that creates an interesting tension in the story.
Survival is also a big theme. Given the dangerous situations in both shows, when combined in crossover fanfiction, the characters are often faced with extreme challenges that require them to fight for their survival. They have to use their respective skills and knowledge, whether it's Sam's research skills or Gwen's knowledge of Cardiff's secrets, to stay alive in the face of threats that are greater than what they're used to dealing with on their own.
One great piece of 'Supernatural' and 'Torchwood' crossover fanfiction is 'The Convergence'. It weaves together the two universes really well, with the characters from both shows interacting in a very believable way. The story has a great plot that involves a common threat that both the Winchester brothers from 'Supernatural' and the Torchwood team need to face. It's full of action and also some really interesting character moments.
Relationships are also a big theme. As I mentioned before, how his relationship with Jack changes is often explored. But also, his relationships with the other Torchwood members. They might be supportive, or there could be some jealousy or confusion among them. And of course, there's the theme of the pregnancy itself - the physical and emotional changes he goes through, like morning sickness, mood swings, and the anticipation of becoming a parent.
One common theme is survival. Given Owen's often - precarious situations in the show, many fanfictions explore how he manages to survive against all odds. For example, in some stories, he has to deal with life - threatening alien encounters alone.
Another common theme is the clash of different mythologies. The show Xander is from might have its own set of supernatural rules and creatures, and when combined with the Supernatural world, there are a lot of interesting interactions. This can lead to stories where the characters have to figure out how to deal with new and unexpected threats that come from the combination of these two different mythologies.
Family and friendship is also a big theme. In 'Supernatural', the Winchester brothers' bond is central, and in 'Btvs', Buffy has her group of friends, her 'Scooby Gang'. In crossover fanfiction, these relationships are often put to the test and developed further. The characters from both shows form new friendships or rivalries, which adds depth to the story. It can be really heartwarming or full of tension depending on how the author writes it.
Family is a big theme. Both shows have strong family bonds. In 'Supernatural', it's the Winchester brothers, and in 'Charmed' it's the sisters. In the crossover fanfiction, these family units often have to work together or face challenges related to protecting their families in the new combined world.
One common theme is the clash of two different worlds. Arrow is mainly about a city full of crime and vigilantes, while Supernatural is all about the supernatural world. So, when they cross over, there's often a struggle to understand each other's ways. For example, Oliver might be skeptical of the existence of demons at first, while Sam and Dean might not be used to dealing with high - tech security systems in Star City.
Redemption is often explored. In Supernatural, many characters are on a journey of redemption, and when Lucifer is added to the mix, the idea of whether he can be redeemed or not becomes an interesting plot point. For example, some fanfictions show Lucifer being influenced by the Winchesters' sense of justice. Another common theme is the disruption of the natural order. Lucifer's presence in the Supernatural universe throws a wrench into the already complex balance of good and evil, heaven and hell, that exists in the series. This can lead to all sorts of chaos and interesting story developments.
A common theme is the exploration of power. Sherlock has his mental power and deductive abilities, while the Supernatural characters have powers like magic and the ability to fight demons. In fanfiction, they might combine their powers to face a greater threat. For example, Sherlock's ability to analyze a situation could help the Winchesters in a battle against a powerful supernatural entity, and the Winchesters' knowledge of the supernatural could help Sherlock understand things he couldn't before.
Another theme is the discovery of new powers and abilities. When the characters from the two universes meet, they might learn new things about their own powers or discover new abilities altogether. Like a Shadowhunter might learn some unique ways of banishing spirits from the Winchester brothers. This theme of self - discovery through interaction with a different world is quite prevalent.