Tsukune's human family might be initially shocked. But if they see how much he loves Mizore, they could gradually come to accept her. They would have to get used to the idea of having a youkai in the family. As for Mizore's youkai family, they might be more accepting since they understand the youkai world better. However, they could also be protective of Mizore and want to make sure Tsukune is worthy of her.
Ginei would be a bit more reserved in his reaction. He might offer some practical advice from his own experiences or knowledge. He'd also be there to protect them if any threats came their way during the pregnancy, as he values their friendship.
Moka would be devastated. She has a strong bond with Tsukune, and his death would likely send her into a deep state of grief and anger. She might go on a rampage seeking revenge against whoever or whatever caused his death.
Tsukune also develops relationships through his own growth. As he becomes stronger or more confident, the harem members notice the change in him. This can make him more attractive to them. For example, if Tsukune was once shy about his abilities but then overcomes his self - doubt and shows great courage in a battle, the members of his harem will see him in a new light. They might start to respect him more and their relationship takes a new turn.
Well, aside from Tsukune, Mizore could be a great addition. She's a snow woman and her cold nature could contrast with Tsukune's new vampire - like heat. Yukari, a young witch, might also be in it. She could either be a friend or a foe to Tsukune. And of course, Akua, a powerful vampire, could play a major role in the fanfiction, perhaps as a mentor or an antagonist to Tsukune.
Moka Akashiya would be a great character to include. She's a vampire herself and could be a love interest for Tsukune, adding a romantic sub - plot. Kurumu Kurono, a succubus, could also be included. Her flirtatious nature would create some interesting dynamics with Tsukune. Then there's Yukari Sendo, a young witch. Her magical abilities could be useful in various situations that Tsukune gets into. For example, when they are facing a powerful enemy, Yukari could use her magic to create distractions or defenses.
First, know the characters well. Tsukune is a complex character with his own growth arc. Make sure to stay true to his personality. Also, understand the world of Rosario Vampire, like the different monster species and their cultures. Then, come up with an interesting plot. It could be a new adventure for Tsukune or a different take on his relationships.
One idea could be that Tsukune discovers a hidden dragon lair. Inside, he finds an ancient spell that accidentally transforms him into a dragon. As a dragon, he has to learn to control his new powers like flying and breathing fire. He might also face challenges from other magical creatures who see him as a threat.
Tsukune harem fanfiction often features Tsukune at the center with multiple female characters having an interest in him. The stories usually revolve around his relationships with these characters, including the development of friendships, rivalries, and potential romances.