One common theme is the development of their relationship. Since they have an interesting dynamic, many fanfics focus on how they grow closer. Another theme could be adventure, as they are often involved in various events in their respective worlds.
Sure. You can start by looking on Archive of Our Own (AO3). There are often many well - written fanfics about different pairings there. Just search for 'Amaya and Janai' and you'll get a list of stories. Some might be adventure - based, others could be more focused on their relationship development.
The characters in the light novel could be extremely well - developed. Each character might have their own goals, dreams, and flaws. Their growth throughout the story can be very interesting to follow. For instance, a character who starts off as shy and timid might gradually become more confident and assertive as the story progresses, which is a very satisfying arc for readers to witness.
One common theme is the exploration of their relationship against the backdrop of the world they live in. Their different cultures and roles within their societies can create interesting tensions and plotlines.
Some fanfictions focus on how they overcome cultural differences. Amaya being from one side and Janai from another, there are bound to be misunderstandings. A popular story could be where they introduce each other to their respective traditions. This not only helps in building their relationship but also in forging a better understanding between their two peoples. They might also have to fight together against a common enemy that doesn't respect either of their cultures, uniting them in a way that was unexpected.
Since I haven't read 'boku girl boku no arbeit novel' directly, I can only speculate. However, from the title, it might deal with the concept of identity ('boku girl' could imply something about gender identity or self - perception). Also, 'arbeit' might suggest themes related to work or purpose in life. There could also be themes of personal growth and the challenges one faces in the context of work and self - identity.
Writers often portray Amaya as a strong and silent type. Her deafness is sometimes used to show her unique perspective. She communicates in her own way and is very perceptive. Janai, on the other hand, is shown as a proud and noble leader. Writers make sure to highlight her regal bearing. For example, in some fanfictions, Amaya's sign language is described in detail to show how she expresses herself without words, while Janai's commands are written in a way that shows her authority.
You can try searching on fanfiction websites like Archive of Our Own (AO3). There are often a lot of fan - created stories about various pairings there. Just use the search bar and type in 'Janai x Amaya' and you'll likely find a good selection.
One similar novel could be 'Kimi no Na wa' (Your Name). It has a unique story about two people who mysteriously swap bodies and their journey to understand each other. Another might be 'Orange' which also deals with complex relationships and personal growth in a rather poignant way. And 'A Silent Voice' is also a great choice as it focuses on themes of redemption and friendship like many good novels in this genre.
Well, without having read 'boku ga yuusha de maou no boku de light novel', it's hard to say precisely. However, from the title, it seems to imply a story where the main character has a dual nature of a hero and a demon king. This could lead to all sorts of interesting plotlines, like internal struggles between good and evil within the character, or perhaps a story where the hero - demon king has to navigate a world that views these two identities as completely opposed.