Obviously, the other Titans like Robin, Starfire, Cyborg, and Raven would be great characters to include. They could be the students in Beastboy's lessons. Maybe the Doom Patrol members could also make an appearance. They were Beastboy's first team, and they could come in to share their wisdom or add some challenges to Beastboy's teaching. And don't forget about the villains. They could be used as examples of what not to do or as obstacles that the Titans need to overcome using what Beastboy has taught them.
The Teen Titans Go! versions of the characters could also be included. Their comical nature could add a fun twist to the education fanfic. For example, the zany antics of those characters could disrupt Beastboy's lessons in humorous ways, but also provide opportunities for learning. Additionally, some of the minor characters from the Teen Titans universe, like Terra or Beastboy's animal friends, could be part of the story. His animal friends could assist him in teaching about the animal kingdom, while Terra could be a character who is either learning from Beastboy or causing some drama in the educational setting.
Well, obviously Naruto and Hinata as Shinachiku's parents. His friends could be the children of other Naruto characters, like Boruto's friends. Maybe the son or daughter of Shikamaru could be his strategic partner in some adventures. Also, the new generation of the Akatsuki could be potential villains in the fanfic.
One idea could be Beastboy teaching other Titans about the importance of environmental conservation. Since he has a connection to animals, he could show them how human actions are affecting different species. For example, he could take them on a journey through a forest that has been damaged by pollution or deforestation, and explain how each of their actions can make a difference in saving these habitats.
Obviously, James and Lily Potter are key characters. Then there's Dumbledore. He was always involved in important matters, so he might be there to offer his wisdom or protection. Sirius Black could also be a character, as he was Harry's godfather. He might be hovering around nervously, eager to meet his godson. And Hagrid, who later played an important role in Harry's life, could perhaps be there to bring some news from the wizarding world to the Potters.
Meredith could be an important side character. Given her history with Derek, there could be some tense moments as she witnesses Addison's pregnancy. It could add an element of drama to the story.
Obviously, Ranma and Akane are prime candidates. Their relationship is central to the series, so a pregnancy between them would create a lot of drama and interesting storylines. Shampoo could also be involved in some way. Maybe she's jealous and tries to interfere, or she could be surprisingly helpful. Genma, Ranma's father, would also play a role. He might have some old - fashioned or comical ideas about the situation.
Obviously Skye herself is the main character. There could be a love interest who is the father of the baby. Her best friend could also be an important character, providing emotional support and practical help like going to doctor's appointments with her.
Pinkie Pie might also be a good choice. Since Pinkie is already a bit of a wild card herself, her interaction with the Bride of Discord could either result in double the chaos or Pinkie Pie somehow taming the Bride's chaos in her own unique, zany way.
Some potential characters could include Fleur Delacour. She's beautiful and has her own brand of magic. Cho Chang could also be part of it. And what about a new character, a mysterious witch from a hidden wizarding village? She could bring in new elements to the harem, like a different type of magic or a unique personality trait.
Obviously, Calvin himself as the main character. His parents could also play important roles, showing how their relationship with Calvin has evolved as he grew up.
Obviously, Kurenai herself could be a central character in the harem. Also, Anko could be a potential member as she is associated with Kurenai and has her own unique personality. Hinata might also be involved as she has a crush on Naruto and could be drawn into this situation due to her connection with Naruto and the overall Naruto - Kurenai scenario.