Another possibility is that the Muggle male is related to a magical object or place in the Muggle world that has some significance in the wizarding world. Luna and Ginny are sent to investigate it. At first, he is skeptical of them, but as they show him real magic, he becomes fascinated. Together, they work to protect the object or place from dark wizards who also want to get their hands on it.
It is not appropriate. These are characters from a fictional world that are often loved by many for their unique personalities and storylines. Creating sexual fanfic about them disrespects the source material and can be offensive to a large number of the fan base.
One characteristic is the exploration of their unique friendship. Ginny is often portrayed as more fiery and Luna as more ethereal, and fanfics play with how these two different personalities interact. For example, in many fanfics, Ginny's protectiveness towards Luna is a common theme.
I really like the fanfic 'Among the Stars with Harry, Ginny and Luna'. In this one, they go on an unexpected journey through a magical portal that leads them to a new, uncharted magical land. The author does an excellent job of developing their relationships further. Harry and Ginny's love is portrayed more deeply, and Luna's unique view of the new world adds a lot of charm to the story.
Friendship. They could have a deep and meaningful friendship where they support each other through tough times at Hogwarts, like when Ginny helps Luna deal with bullying from other students.
Love and relationships can also be a theme. Harry and Ginny's romantic relationship is a big part of it. And Luna's role in their relationship, whether as a friend who gives advice or as someone who helps them see things in a different way, is often explored in these fanfics.
Another one is 'The Kiss Under the Stars'. In this fanfiction, Luna and Ginny are stargazing on the Hogwarts grounds. The author does a wonderful job of building the mood. The kiss in this story is very spontaneous and full of passion. It's a short but sweet fanfiction that captures the essence of their relationship quite well.
The emotional depth is crucial. The kiss should be more than just a physical act. It should be a moment of deep connection between the two characters. The fanfiction should make the readers feel the love, the hesitation, the excitement, and all the complex emotions that come with that moment. Also, the writing style should be engaging, whether it's flowery or more straightforward, it has to draw the reader in.
Begin with a conflict. Maybe the Muggle male has unknowingly gotten himself into trouble with a dark wizard. Luna and Ginny hear about it through the grapevine in the wizarding world. This immediately sets up a situation where they need to rescue him. You can then describe their first encounter, how Ginny might be more cautious while Luna is more curious about this Muggle in trouble.
Romance can be a theme as well, although this might be less common. Some fanfiction might explore a romantic relationship between them. It could involve a slow - burn type of romance where they start as friends and gradually realize their deeper feelings for each other. This often involves exploring their emotional growth and how they come to terms with their feelings in a world that may not always be accepting of same - sex relationships within the context of the story.