To expand on this: Shirou not having a goal beyond wanting to help people is fine. that does not set the plot. There are plenty of main characters who's singular goal is very vague or short term. I call these 'Reactionary Protagonists." They tend to stay where they are, until they here something that they need/want to help with, but in these cases, someone, somewhere has a goal. There needs to be a big bad, and he needs to have plans, if the Protagonist isn't going to have any of his own. What I'd do, is sit down, and figure out who you want to be the big bad of the fic. What is their final goal? What plans will the implement? How do they influence the storyline? This allows you to sprinke hints and clues about what is going to happen. Having an MC with a simple goal as "I want to protect/help these people," is fine, because they are not the instigator of the plot. So, who is Shirou's ultimate enemy here? What enemies does he have? Who's out to get him, or the people around him?