One interesting character could be Zenon's best friend. You can explore their friendship more deeply, like how they support each other through tough times in the 21st century. Another could be a mysterious scientist she meets. This scientist might be working on a top - secret project that Zenon gets involved in. And there's also the possibility of writing about her school teacher who has a really unique teaching style and challenges Zenon in different ways.
To develop Protozoa, think about how it interacts with its environment. If it's in a lab setting, how does it react to different stimuli? For Zenon, show her growth. At first, she might be a bit hesitant about her relationship with Protozoa, but as the story progresses, she becomes more confident and protective. You can also develop their relationship by having them face challenges together, like when other scientists question Zenon's attachment to Protozoa.
One idea could be that Protozoa, being a microscopic organism in nature, has some sort of special connection to Zenon. Maybe Protozoa is a sentient being in this fanfiction and can communicate with Zenon telepathically. Zenon could be on a scientific mission to study Protozoa but ends up learning life - changing lessons from it.
One popular storyline could be Zenon's adventures in a future world filled with new technologies she has to adapt to. For example, she might face challenges with advanced AI systems that are malfunctioning. Another could be her relationship with other characters, like a new friend from a different planet who comes to visit Earth in the 21st century. And then there could be storylines where she uses her unique skills to solve global problems, such as environmental issues.
Well, El Cid has a basis in history. Rodrigo D铆az de Vivar was a real person, but the stories about him have likely incorporated fictional elements over time to make them more captivating.