Tatiana Xavier in the 'Tatiana Xavier Secret Story' could be the main protagonist. She might be someone with unique qualities or experiences that are central to the story. It could be that she has a past she's trying to hide or a goal she's striving for secretly. Since we don't know the nature of the story, she could be a real - life figure that the story is based on or a completely fictional creation.
Toge Inumaki is important too. His special cursed speech ability makes him stand out. Also, the principal of the school, Masamichi Yaga, is likely to be important as he is in a position of authority and has an influence on Gojo and the other students. There could be other characters like the members of different clans that also play roles in the complex web of the story.
One way to develop their relationship is through acts of kindness. Maybe Xavier gives Wednesday a piece of his art that he made especially for her, which shows that he sees her in a special way. Wednesday, in turn, could protect Xavier from a bully at school. Another aspect could be through humor. They could start making inside jokes based on their strange experiences at school. As they get more comfortable with each other, they might even start to develop feelings that are more than just friendship. For instance, Xavier could find himself getting jealous when another student shows interest in Wednesday, which would be a sign of his deeper feelings for her.
Charles Xavier's fate in the comics is not straightforward. Sometimes he's alive, sometimes he's dead. It all depends on the writer's creative decisions and the direction of the story at that time.