how to create the role of perfect agency?

It's someone who takes "heroic responsibility". Source:

"You could call it heroic responsibility, maybe," Harry Potter said. "Not like the usual sort. It means that whatever happens, no matter what, it's always your fault. Even if you tell Professor McGonagall, she's not responsible for what happens, you are. Following the school rules isn't an excuse, someone else being in charge isn't an excuse, even trying your best isn't an excuse. There just aren't any excuses, you've got to get the job done no matter what. That's why I say you're not thinking responsibly, Hermione. Thinking that your job is done when you tell Professor McGonagall - that isn't heroine thinking. Like (SPOILER) is okay then, because it isn't your fault anymore. Being a heroine means your job isn't finished until you've done whatever it takes to (SPOILER), permanently. You can't think as if just following the rules means you've done your duty."

So, I guess watching superhero movies, and imagining yourself being one, could be a good start. Preferably movies where the superhero is not defined primarily by their supernatural powers, but by taking action where others don't. In other words, less Superman, more Batman.