There could be a nocturnal creature, like a vampire or a werewolf, who has its own story and relationships that unfold during the dark of night. Vampires, for example, might be dealing with their eternal existence and the hunt for blood under the cover of darkness, while werewolves could be struggling with their dual nature that is more pronounced at night.
A young, curious orphan who often sneaks out during the dark of night and discovers a hidden world in the city, filled with all sorts of strange characters.
An old, wise hermit who lives on the outskirts of a village near a dark forest. He has spent years studying the secrets of the shadows and can guide others who are in trouble related to the shadowy mysteries. His knowledge would be crucial in the story.
A young and curious scientist. She is constantly exploring the remnants of the old world, trying to find ways to use the forgotten knowledge to improve the current situation. Her inquisitive nature often gets her into trouble but also leads to great discoveries.
The characters in The Dark Night include Zhao Mei (Jiang Shuying), Li Dongming (Tong Dawei), Dong Yue (Zhang Chao), Liang Danning (Lan Yingying), Qiao Hailun (Han Qingzi), Silent (Wang Zhifei), and Xu Yuntian (Wang Yaoqing).
A young Twi'lek girl with extraordinary Force - sensing abilities could be a new character. She could be an orphan who was raised in the slums of a planet but discovers her powers and is sought after by both the Jedi and Sith. Another could be a Mandalorian warrior who has his own code of honor and gets involved in the Jedi - Sith conflict in Dark Destiny. And a droid with a malfunctioning protocol but a unique ability to detect dark side energy could also be an interesting addition.
A pyromancer could be an interesting main character. They have a natural affinity for fire, so they might be either trying to preserve the Age of Fire or manipulate it for their own ends. Their powers could lead them to discover secrets about the Age of Fire that no one else knows.
Cynder could be a key character. She has a connection with Spyro and could play a role in helping Dark Spyro either come to terms with his powers or in fighting against a common enemy.
Sakura could be one of the characters in the harem. She is strong - willed and her medical ninja skills could be useful in the story. Hinata is also a likely candidate as she has always had a deep affection for Naruto. Her gentle yet powerful Byakugan abilities would add to the group dynamics.
Without reading 'the dark of night kuroshitsuji fanfiction', it's difficult to say definitively. However, based on the Kuroshitsuji series, Ciel and Sebastian are the most prominent characters. In a fanfiction set at night, they could be the main focus. Ciel's vulnerability and his need for Sebastian's protection might be emphasized during the night. Sebastian's loyalty and his demonic powers would also be crucial elements. Additionally, characters like Grell Sutcliff or Undertaker could also potentially be main characters in this fanfiction, depending on the plot. For example, Grell's obsession with Sebastian might lead to some interesting night - time encounters in this fanfiction.
Sasuke could be one of the main characters to interact with Dark Naruto. Given their complex relationship in the original Naruto series, Sasuke might be either drawn to help Dark Naruto because of their shared past, or he could see Dark Naruto as a threat to his own goals and power. They could have some intense battles or deep conversations about the nature of power and the path they've both chosen.
Obviously, Hiccup and Toothless are the main ones. Astrid could also be in it, maybe she tries to figure out what happened to Hiccup and how to turn him back. There could also be other Vikings who are either scared or intrigued by the baby Night Fury that used to be Hiccup.