Growth is also a theme. Noelle crying might be a turning point for her character. It could be the moment she decides to be more open about her feelings, both to Asta and to herself. This can lead to her personal growth in the fanfic.
Perhaps in the fanfic, there is a misunderstanding. Asta might accidentally say something that makes Noelle think he doesn't care about her. This could lead to Noelle crying, and Asta then has to figure out what he said wrong and make it up to her. It could be a story about miscommunication and making amends.
Since lemon fanfics are inappropriate, we should focus on their general characteristics from the official story. Asta is highly determined and energetic, always striving hard despite his lack of magic initially. Yuno, on the other hand, is more calm and has a natural talent for magic. They both have a strong bond as rivals and friends.
Noelle could be a great addition. Her water magic is quite powerful and she has a complex relationship with both Asta and Yuno. She could be a source of both support and conflict in the fanfic. Another good character is Luck. His lightning magic and his rather unpredictable nature can add a lot of action and excitement to the story.
Asta would likely bring a new level of determination to the Crimson Lions. His never - give - up attitude could inspire the team members during tough battles.
Asta is still alive in the manga. The story keeps evolving with him at the center of the action. There have been many difficult situations, but he manages to overcome them without dying.