I had an idea for a story which I feel fits very close with Studio Ghibli style stories, especially ones like spirited away. I really want to expand it while keeping the Miyazaki feel, and have already come up with some interesting character concepts, but I'm really limited by the need to better define the central abilities that drive the story.
In particular I'm having trouble coming up with powers that are undefined enough to leave the protagonist unsure how to use them, weak enough to not make things to easy on the protagonist, and yet strong enough that the protagonist can play an important role in the climax to show her character development.
Premise
In this world there are people I'm currently calling Fortune Tellers (I don't really like the name, I just can't think of better yet), who are closely linked to Fate, which is an important element of this world. Fate seems to happen around tellers, meaning that spectacular events, extraordinary strokes of luck, and generally the sort of things that seem to go beyond coincidence and into the realm of Fate constantly happen around tellers. However, Fate is a neutral force, neither good nor bad, and as such the spectacular events around Teller's are equally a mix of good and bad.
Someone talking to a Teller may trip and and stumble into the arms of their true love, but they may also stumble knock over a man carrying the expensive prototype for an invention which will cure world hunger and destroy it, getting themselves ostracized by the famine riddled town.
Teller's may have a strong sense of Fate as well. They may look at someone and know they are Fated in some way (ie something big or important will happen associated to them). They may see two people and realize that there is some sort of Fate between them, something will happen between the two of importance. However, they don't have full control over this, sometimes they will notice it sometimes they won't, and again they only know that Fate will happen, not when or how, or if it will be good or bad Fate.
People aren't sure how Teller's work exactly, in fact there are many different and often conflicting theories and more myth then fact about them. Some believe that a Teller causes Fate to happen by being in an area, other's think that Tellers are simply drawn towards places where important Fateful things were likely to occur anyways, causing them to happen to be there when it happens, and others think that Fate is a cosmic plan that controls tellers as much as others, the tellers are there because they were Fated to be just as much as the person who was Fated to have a Eureka moment after accidentally dropping his gold plated watch in a bathtub and watching water spill out of it.
The response from people to Tellers is varied. It's not uncommon for people to come to Teller's to ask for advice or help. Some believe that since the Teller's can sense Fate they may be able to steer it slightly, though there are lots of myths and no one is certain how or if they can. Someone may come to a Teller and ask them which baby name feels right to them, or to pick between two hands which each hold a slip of paper with a course of action their considering on it. The idea is that the Teller may be able to sense which of the two names, or actions, is associated with a better Fate and pick the one that will end better. two young teens who are dating may go to a teller and ask if they are Fated to be together etc. I may expand on this more, but the idea is that some turn to the tellers to try to take advantage of their sense of Fate for good, but it's not as easy as having someone that can see the future. A teller can't be certain that only positive things will happen, and how much power the teller actually has to effect things isn't entirely certain either; though ideally I'm leaning towards them having some ability to have a positive effect if they do things right.
While people often come to the Teller for advice the general opinion of people towards Teller's vary significantly. Some may blame (or thank) a teller for some bit of Fate that happened to them before, and the amount that a Teller is credited for being able to influence Fate varies. The one thing that is generally true is that, while many may come to a Teller for help when they need it, few want to spend a long length of time with them. Teller's bring lots of fate, both good and bad, and that leads to a chaotic life. Not all of the Fate will be bad, but the consensus seems to be a long boring life is better then a crazy, if interesting, life of constant ups and downs of Fate that come with being around a Teller.
Protagonist
The hero is, in keeping with the Miyazaki feel I mentioned, a younger girl, I'm not set on age, but no older then mid teens and quite likely younger. Teller's discover their abilities during a Fateful, awakening, and it usually happens in their 20's. The hero has her awakening at a much younger age. This may mean that Fate is even stronger around her then others.
She is going to be a strong, though young, hero. She is still young and emotional, and thus is hurt to an extent by the fact that people don't tend to want to stay around her because of fear of Fate happening, and even more that some blame her when bad Fate occurs, but she will grow strong enough to handle this. She has, from the beginning, a strong desire to help people. In particularly she idolizes to her much older brother who was well loved for all the good work he did before he left to help people further away, and she wants to do the sort of good he did.
The ambiguity of most Teller's powers is intentional, I want to show the struggle of her not knowing how to be a Teller. People come to her and ask her to pick between two decisions based off of what feels 'right', but she doesn't know how she should tell what is right. She want's to help, but worries that she is just guessing instead of actual helping.
The story should, in miyazaki tradition, focus the protagonist's growth and maturing. I'm willing to work with her growth in a few ways, but growing more confident in her own decision making and abilities, rather then 'helping' by going along with whatever anyone else wants, and working to learn how to use her ambiguous abilities to help others are likely key parts of it.
One of the side characters she has is a scientist who wants to understand Tellers and their link with Fate, who may help her to try to figure out what she actually can do vs what is Myth. However, even with the scientist help it should mostly be a journey of self discovery, the scientist doesn't have the answers or a way to set up proper controlled tests, so she is simply discovering along with the girl.
What I'm Missing
The idea of Teller and Fate is not completely defined, as I said to an extent I want the world to not fully understand the implication and limits of these things so that it has to be a journey of discovery for the girl. However, I'll ultimately need a climax in which the girl has to do something to help others to show her growth. Her power's can't be completely ambiguous or worthless if she is going to be the person who has to do something, despite having other more physically competent people with her. At the same time her abilities can't be an "I WIN" button either, I want to show her being brave and taking action in a situation where she has to have confidence in her own ability to judge the situation, even if the answer isn't completely obvious.
I need to better define what I want a Teller to actually be able to do if I'm going to decide how she will grow and what an appropriate climax is. I'm pretty flexible on specifics so long as I can both have her struggling with unknown abilities at first and yet developing enough to be relevant by the climax, while still feeling more like a strong willed girl doing her best rather then an x-men with magic Fate powers.
I have toyed with giving Teller's abilities beyond the general Fate ones, but only if they weren't too powerful. I had originally thought of saying Teller's gain some other weak magic like abilities that develop over time, with the Girl's being particularly weak due to her age, but it was hard to get something thematic that wasn't too powerful.
The one idea I thought that may work is the idea of having them able to see or interact with spirits/ghosts of some sort as well, with the climax partially being about quelling upset spirits before they cause harm. However, I had a hard time fitting it in with the other Fate ideas in a way where the ability to interact with spirits didn't monopolize the plot, but also didn't feel forced in just to justify having a relevant power to solve whatever the conflict was in the climax. I think it's partially because I have a hard time thinking of a good way to interact with spirits/ghosts that I feel is interesting.