One common theme is the struggle against different worlds' expectations. Since Loki is from Asgard and Jane is from Earth, their relationship often has to deal with the differences in their cultures and the opinions of those around them.
Well, cultural exchange is a common theme. Jane gets to experience Asgardian culture through Loki, and Loki gets to understand Midgardian (Earth) ways better. This can lead to some really fun and educational moments in the fanfictions. Another theme is the clash between science and magic. Jane is a scientist, and Loki is a master of magic. Their different worldviews collide and combine in interesting ways. Also, the theme of protection often comes up. Loki wants to protect Jane from various threats, whether they be from Asgardian enemies or from Earth - bound problems, and vice versa.
The theme of how different worlds (Asgard and Earth) react to the pregnancy also comes up often. There are cultural differences and power dynamics at play. The fanfictions may explore how they navigate these differences while preparing for the arrival of their child.
A recurring theme is the blend of two worlds. With Loki being from Asgard and Jane from Midgard, their baby represents a union of these two very different places. Fanfictions often explore how this affects the baby's upbringing, the couple's relationship, and the relationships between the two realms. For example, there could be cultural clashes or new forms of magic and science emerging from this union.
Another theme is the clash of cultures. Since Loki is from Asgard and Jane is human, their different backgrounds play a role in how they approach the pregnancy, like in some fanfics where Asgardian traditions around childbirth are introduced.
One common theme is the 'opposites attract' concept. Loki, the complex and often mischievous Asgardian, and Jane, the intelligent and curious human scientist, are very different, but that draws them together.
One common theme is the clash of different worlds. Loki is from Asgard and Jane is from Earth, so their different cultures and ways of life often create interesting dynamics. Another theme is redemption. Loki has a complex past, and in many fanfictions, he tries to find redemption through his relationship with Jane.
Power dynamics is also a common theme. Loki has his powerful and often dark magic, and Jane is just a mortal. How they interact in terms of power, with Loki being so much more powerful yet being affected by Jane in some way, is something that many 'dark loki and jane fanfiction' explore. For example, Loki may use his power to protect Jane in his own dark way, or his power may accidentally harm her, leading to conflict and growth in their relationship.
One common theme is redemption. Loki often has a journey of self - discovery and trying to make up for his past wrongs, and Jane can be a part of that process. For example, in many fics, Loki sees Jane's goodness and it makes him want to be better.
Love stories are quite common in Loki fanfiction. It could be a romantic relationship with another character from the same universe or an original character created by the fanfiction writer. His powers are also a big theme. Writers might explore how he uses his powers in different situations, or how he discovers new powers. Additionally, the theme of Loki being an outcast is often explored, as it's an important part of his character in the original works.
One common theme is redemption. Maybe Odin is trying to make up for past wrongs towards Loki. Another is family drama, as their relationship is complex in the original mythology.