Overcoming obstacles is also a big theme. There could be things like pack politics, family issues, or other supernatural threats that they have to deal with as a couple. Their bond as mates gives them the strength to face these difficulties.
Common themes would include the power dynamics between Derek and Stiles. Since Derek is in heat, there might be a shift in the power balance in their relationship. There could also be a theme of protection. Stiles might feel the need to protect Derek from potential threats while he's in this state. And of course, love and attraction are likely themes, as the situation could intensify their feelings for each other.
One common theme is the discovery of love. They often start off not realizing their feelings and then gradually come to terms with their deep love for each other. Another theme is the power of acceptance. Since Stiles and Derek are different in many ways, their journey towards accepting each other completely is often explored.
One common theme is the discovery of their mate bond. It's often a journey of self - discovery for both Stiles and Derek as they figure out what it means to be mates.
One common theme is loyalty. They often show how Peter and Stiles are loyal to each other no matter what. Another is the theme of protection, as they protect each other from various threats.
One common theme is the idea of redemption. Derek might be seen as a character who has a past to make up for, and Stiles helps him in that journey. Another is the theme of trust. They have to learn to trust each other despite their differences. And love, of course, is a major theme as their relationship develops.
One common theme is self - discovery. Since Derek is a complex character, many fanfictions focus on him learning more about himself. Another theme is friendship. Writers often explore the relationships he has with other characters in the story. Also, adventure is a popular theme. Derek is often put into exciting and dangerous situations in fanfiction.
One great 'Stiles x Derek Mates' fanfic is 'The Bond Between Us'. It beautifully explores their relationship development. The story delves into how they come to terms with being mates and face various challenges together in the supernatural world of Beacon Hills. It has some really touching moments where their connection is palpable.
The theme of self - discovery also runs through these fanfics. Stiles, in particular, may go through a process of self - discovery as he experiences the physical and emotional changes that come with mpreg. He has to learn to adapt and understand himself in a whole new light, which in turn affects his relationship with Derek.
The theme of growth is also prevalent. Stiles may grow in terms of his understanding of Derek and their relationship. He might become more empathetic or stronger in the face of the pain Derek has caused. Derek, on the other hand, might grow in his ability to control his actions and emotions better.
Love and acceptance is also a big theme. They often have to deal with others' opinions of their relationship, whether it's from their friends or the wider supernatural community. And they have to learn to accept each other's flaws and differences as they fall in love. It makes for some really interesting and emotional storylines in the fanfiction.