She might be a character representing the general state of women in a particular society or situation. Maybe she's a symbol for all those who are oppressed and are finally finding their voice to scream out in protest.
Their relationship in the fanfiction is likely to be full of mutual understanding. Since they are getting married, they must have a deep connection. Takato might be the more gentle and patient one, while Rika could be the strong - willed partner. They balance each other out.
In the manga, Inumaki has distinct abilities and a quiet nature. Yuta is depicted with significant strength and a sense of purpose. Both characters have their own arcs and development.
Maki in fanfiction usually has a fierce loyalty to her friends, especially Yuta. She is the type to fight for what she believes in. Yuta is sometimes portrayed as being a bit naive in the ways of the world outside his own small circle, but his pure heart makes him endearing. In many stories, their different personalities create an interesting dynamic, like in a story where Maki's boldness gets them into a risky situation and Yuta's calm thinking gets them out.