One common theme is the discovery of their bond. It usually involves a lot of emotional turmoil as fem Harry comes to terms with having Marcus as her mate. Another theme is the way their relationship affects the people around them. For example, how their friends and enemies react to this new development.
Power dynamics might also be a theme. Marcus may have certain powers or a position within the story's world, and how that affects his relationship with Bella could be explored. For example, if there are other characters who oppose their union because of Marcus' power or status. Another common theme could be the struggle against outside forces. There might be other characters or groups that try to keep Bella and Marcus apart, creating conflict and drama in the story.
Another theme is the power dynamics. Harry has her own magical abilities which are different from the elven magic. When combined with Thranduil's leadership and power among the elves, it creates a complex relationship where they both have to learn to respect and utilize each other's strengths. Also, the theme of love against all odds is quite prevalent. Given their different backgrounds, coming together in a relationship is not easy, but their feelings for each other often prevail.
One common theme is the exploration of different cultures. Since Harry comes from the wizarding world and Legolas from the elven world, there's a lot of room for showing how these two different cultures interact. Another theme is the power of love that can bridge different species and worlds.
The theme of self - discovery is also prevalent. Fem Harry discovers more about herself through her relationship with Remus. She may find new aspects of her magic or her identity as a woman. And of course, there's the theme of loyalty. They are loyal to each other despite the odds and the difficulties they face.
One popular 'fem Harry is Marcus mate' fanfiction might be 'Destined Bond'. In this story, the author creates a really interesting world where fem Harry and Marcus have a unique connection that develops over time. It has great character development and a really engaging plot.
A common theme is the exploration of power. Since Fem Harry is connected to Salazar, there's often a focus on her inheriting or accessing some of his ancient and powerful magic. Another theme is identity. She has to reconcile her modern self with this new, ancient connection to Salazar.
A lot of these fanfictions have the theme of redemption. Draco, who was initially a bit of a bully, often goes through a process of redemption as he realizes his feelings for Fem Harry. Also, the theme of secrecy is common. Because of their unusual relationship, they often have to keep it a secret from others in the wizarding world.
Another theme is power dynamics. Lucifer is a very powerful being, and fem Harry usually has her own set of powers or qualities. So, how they balance the power in their relationship is often explored. For example, in some fics, Harry might be initially intimidated by Lucifer's power but then learns to hold her own.
A common theme is the clash and then the melding of two different universes. Since Harry comes from the wizarding world of Harry Potter and Loki is from the Marvel universe, there's often exploration of how their different powers and cultures interact. Another theme is the development of their relationship, which usually starts with some sort of misunderstanding or conflict due to their very different personalities and backgrounds.
One common theme is the discovery of their relationship. Since it's a unique pairing, often the fic will focus on how they come to realize they are mates. Another theme is the clash of their different worlds. Harry comes from the wizarding world and Kisuke from his own world, so there's often a lot of exploration of how their two worlds' cultures and powers interact.