Since I don't know the exact story, it's hard to say the main themes. But if we assume based on the phrase, themes could be about contrast and inversion.
Not having knowledge of the specific 'black as day white as night' original story makes it tough to be definite about the themes. But thinking about it generally, themes of mystery and enigma could be present. Why has this strange state of 'black as day white as night' occurred? There might also be themes of struggle, as the characters might be struggling to adapt to this new and abnormal state of day and night. Additionally, themes of discovery could be there, as they might be on a quest to find out the cause and solution to this unusual situation.
I'm not sure which specific 'black as day white as night' original story you are referring to. There could be many fictional or cultural stories with such a concept. It might be a very specific or regional tale.
Here are some recommendations for novels similar to Black and White: "Back to the Light, Into the Dark"-Author: Starry Moon on a Snowy Night. This novel was a fantasy, an oriental fantasy. The protagonist rose in the night and broke the shackles of fate. Although it wasn't written by Night de Aries, the writing style of this novel was very good and the plot was very attractive. I hope these recommendations will meet your needs.
The uniqueness might lie in its title's play on the normal associations of black and white. Usually, we say 'black as night' and 'white as day'. Reversing it makes it stand out. It could imply a story that turns the typical ideas of good and bad, or light and dark, on their heads.
Well, in the original story, one of the themes is transformation. The White Snake transforms into a human form to experience human life. Also, there is the theme of good and evil. While the White Snake is mostly good - hearted, she still has to face the prejudice from the human world which often views snakes as evil.
I'm afraid I can't determine the main characters in 'black or white original story' without more details. However, if it's a story about race relations, the main characters might be from different racial backgrounds, one being black and the other white, and the story could revolve around their interactions, experiences, and how they deal with the social constructs around their races.
In the black wolf white wolf story, the themes of competition and cooperation are likely to be present. They could be competing for the same resources such as prey or a good den. But at the same time, they might realize that by cooperating, they can better defend against larger predators or other threats. Also, there could be a theme of identity. The black wolf and the white wolf may have different identities within their own species or in the eyes of other animals due to their distinct fur colors.
One main theme could be racial cooperation. Given it's about black and white airmen, it must show how they worked together.
One possible theme could be diversity. Since they are different, it might explore how their differences are both a source of beauty and a cause of initial friction.
I'm not sure specifically which 'black as day white as night fanfiction' is out there. You could try searching on popular fanfiction websites like Archive of Our Own or FanFiction.net. Just use those keywords in the search bar and see what comes up.
Love and sacrifice. The love between the White Snake and Xu Xian is a central theme. The White Snake is willing to endure great hardships for their love. Also, the conflict between the human and the supernatural is another theme as the White Snake's true identity brings many challenges.