One common theme is the power struggle. The vampire and the black widow both have their own forms of power, and often in these fanfictions, they clash or collaborate based on that power. Another theme is the idea of the outsider. Both characters can be seen as outsiders in different ways, and their journey to find a place in a world that doesn't fully understand them is often explored.
Another theme is the exploration of power. As a vampire, she gains new powers such as super strength and enhanced senses. Fanfictions often explore how she uses these powers, whether for good or for her own self - interest. Some stories might have her using her powers to take revenge on her enemies in a more brutal way than before.
One common theme is redemption. Since Natasha has a dark past, many fanfictions explore her journey towards making up for the things she's done. For example, she might try to save people she once targeted.
The theme of loyalty also comes up frequently. Whether it's loyalty to the Red Room in her past, or her newfound loyalty to the Avengers later on. Fanfictions play around with how these loyalties shift and develop over time, especially when looking at her past experiences.
A frequent theme is adventure. Writers often put them together in various action - packed scenarios, either in the context of existing Marvel storylines or in new, original settings. There's also the theme of forbidden love, as they come from different 'worlds' in the Marvel universe, Loki being a god and Black Widow a human - enhanced agent. This adds an element of tension and drama to the stories.
Another theme is the power of friendship. They come from very different backgrounds, but in fanfiction, they often form a strong bond. They support each other in battles and in personal growth. Like when Black Widow is in a tough situation and the Hulk comes to her rescue, showing that they have each other's backs.
One common theme is the exploration of their different abilities. Quake has her seismic powers and Black Widow her combat and espionage skills. Fanfictions often play with how these can be combined or contrasted.
One common theme is loyalty. Given Black Widow's past and her complex relationships, loyalty within the GXG relationship is often explored. For example, in many stories, they have to prove their loyalty to each other in the face of danger or betrayal.
One common theme is the clash of their different fighting styles. Black Widow's more stealthy and calculated approach against Daredevil's more impulsive and street - level brawling.
A common theme could be mind control and the power dynamics it creates. Since it's about hypnosis, often the story explores how the Black Widow's mind is affected or how she uses hypnosis on others.
Another theme is redemption. Sometimes the Hulk is portrayed as a character seeking redemption for the destruction he's caused, and Black Widow helps him on that journey. It's about how they can find a new purpose together. A lot of fanfictions also play with the idea of them being outsiders in the Avengers group, and how they form a special bond because of that.