Heroes or what?
It seems when people think of the powered among humanity, they start to pigeonhole them: heroes help and villains hinder, that sort of thing. There must be bad for the good to flourish. Oft-times, it seems this is based on a belief in mankind in general that is shown to be true again and again. There are those who commit atrocities and those who will step in to fight against them.
What if your characters simply don’t want to be a part of this age-old circle of existence? What if their powers don’t match with what it is that they love to do? I am not necessarily speaking of your primary characters here, as one assumes that they will have some motivation to perform heroic tasks, but your minor characters – those that normally don’t get a second glance from your readers. The window dressing. The extras. NPC’s, to borrow from the gaming world.
Suppose a medical doctor develops vision on a microscopic scale. That would aid him immensely in fine surgery, and would be a boon to his career. What if, instead, he suddenly became able to ignite his molecules and sheath himself in a flame? Not so helpful in the OR. Certainly, he could become a hero and use that flame to enforce justice (on whatever scale), but perhaps he has no reason to. It could easily come up in a story should he ever be forced to use it in a defensive manner, but for the most part it stays dormant. No one knows about this ability except good ol’ Doc Molotov. You, as the writer, know it is there and can employ it at your leisure, but unless some reason pops up to do so, his abilities will remain in the background.
The same could apply to the CPA who develops enhanced strength, or the chemist who finds herself able to make it snow. Many people, even were they handed some strange ability, would want little more than to be left alone to continue their lives unmolested. This is exponentially more the case in any setting where parahuman abilities must be registered or licensed.
These characters can be interesting additions to your tales. Let a hero find out about the aforementioned CPA by way of being rescued from a collapsing building (“Large pieces of rubble mean nothing to me, sir.”). It’s a minor thing for your main character, but to the CPA, this is life-changing. He doesn’t want anyone knowing, because to him, it will simply lead to complications he does not want. How your character deals with that knowledge will say a lot to your readers about them. It also opens up avenues of characterization for the NPC. Perhaps the hero needs an accountant in his private life. They might then seek out the one who had saved them. After all, if you’re going to pay someone for a job, why not make it the person who kept you from dying?
In the next category are those with powers they put to use on a daily basis but not for reasons philanthropic or malign. That fellow down the street with the ability to detect weaknesses, for example. Why would he become a fighter, when construction companies would pay him a fortune to inspect skyscrapers? Little Irma Malone, the lady who can shape rock at will? If her sculptures aren’t enough to keep her coffers filled (and of course they would be – who wouldn’t want to buy a one-of-a-kind sculpture from the world renowned Irma?) then the money she makes from her consulting gig with those mining companies certainly is. The power to change molecular structures? Sure it could make a battle interesting, but what about creation of the most desired thing in a classic superhero universe: the costume! Weather control? Plant growth? Farmers would line up for your help.
In a world filled with enhanced powers, there will be those who have little use for them, and there will be those who use theirs simply for their own reasons. While they may seem unimportant in the grand scheme, their presence helps to flesh out the backdrop of your universe.