First, establish a strong character for the human girl. Give her unique qualities and a clear goal. For example, she could be on a quest to save her family from the dark forces in the Black Butler world. Then, introduce the butler in an interesting way, highlighting his mysterious nature. Their initial encounter should be memorable.
Build a rich world around the Black Butler and human girl relationship. Include other characters from the Black Butler universe, each with their own motives and secrets. Develop the relationship between the butler and the girl gradually. Show how they learn from each other and change as a result of their interactions. A good plot also has a climax, where the biggest conflict is resolved, and a satisfying ending that ties up all the loose ends.
To write a compelling plot for Blue Diamond x Human Fanfic, you need to think about the characters' goals. The human might want to understand the gem world better, while Blue Diamond could be seeking something from the human like a new perspective on life. Then, add some mystery. For instance, there could be secrets about Blue Diamond's past that the human helps her uncover. Also, don't forget about the emotional arcs. The human could start off scared of Blue Diamond but end up loving her, and Blue Diamond could go from being indifferent to humans to being deeply attached.
There's also the 'transformation' trope. The human girl might start to change, either influenced by the butler or the events in the Black Butler world. She could become stronger, more confident, or even develop some supernatural abilities. This trope can be used to show her growth and development within the story.
To write compelling character interactions in this fanfiction, focus on the existing relationships in Black Butler. For Ciel and Sebastian, play with the power imbalance. Let Ciel try to assert his authority in the 7 - minute period while Sebastian subtly challenges it. For other characters, like the servants, show their loyalty and naivete. They might be excited or nervous about the game, which can lead to humorous or endearing interactions.
The girl OC could be a noble from a foreign land who comes to England and crosses paths with Ciel and Sebastian. She has her own motives for being there, perhaps to find something that was lost from her family. She ends up getting involved with the Phantomhive's business, and Sebastian has to protect her while also trying to figure out her true intentions. There could be a lot of drama as she tries to navigate the dangerous world of the Black Butler universe, and she might also develop a romantic interest in either Ciel or Sebastian, which would add more complexity to the story.
To write a great fanfiction about Ciel's little sister, start with a strong backstory. Explain how she ended up in the Phantomhive family. Was she adopted? Or is there a more mysterious origin? Build on her relationships not just with Ciel, but also with the servants. For instance, a budding friendship with Finny could show her kind - hearted side. When it comes to the plot, make it engaging. Maybe she discovers a conspiracy that threatens the family and has to use her wits to solve it. Don't forget to give her growth throughout the story. She should change and develop as she faces different challenges. And use vivid descriptions to bring her world to life, whether it's the grandeur of the Phantomhive manor or the seedy underbelly of London.
Create a vivid setting. If it's a post - apocalyptic world where the Hellhound is trying to survive, describe the ruins and the danger lurking around every corner. Also, develop interesting relationships. Maybe she has a rivalry with a vampire - like monster girl that slowly turns into friendship.
A 'Black Butler Girl in the Garden Fanfic' might focus on a female character in the Black Butler universe within a garden setting. It could explore her experiences, relationships, or perhaps some mystery in that particular location. For example, it might be about a new character who has a special connection to the garden, like she discovers some hidden secrets there that are related to the main plot of Black Butler. Or it could be about an existing female character's moment of self - discovery while in the garden.
To write a compelling male human character in a Gardevoir x Male Human fanfic, give him a unique backstory. Maybe he was once a Pokémon trainer who had a bad experience and quit, but Gardevoir brings back his love for Pokémon. Also, give him some distinct personality traits. For example, he could be really curious about Gardevoir's psychic abilities and always asking her questions. Another important aspect is to show his growth throughout the story. He could start off as a bit of a coward but become brave as he faces challenges with Gardevoir.
When creating the OC human, it's important to think about their growth throughout the story. Start with them being naive about Celestia's world. As the story progresses, they should learn and change. For example, they might start out being afraid of magic but by the end, they master a certain type of magic. Their goals and desires should be clear. If they want to find a way back home to the human world at first but then start to fall in love with Celestia's world and want to stay and protect it, this shift in their goals can create an interesting and complex character arc.
Perhaps she is a magical being. In the 'Black Butler' universe, there are all sorts of supernatural elements. She could be a fairy or a nymph who was trapped in the garden. Sebastian and Ciel might initially be suspicious of her but then find out she can be an ally in their battles against other dark forces.