Group gets superpowers, but one member gets left out. After a long period of time, that member gets their own abilities.
A group of people (generally teenagers) encounter something that gives each of them their very own superhuman abilities. Except one. This person has no powers whatsoever, and gets either jealous or depressed. Months or so later, something life-threatening causes the loner to unearth their own superpowers, which are usually stronger than any other group member's.
Hello, Unknown Troper. You'll need to get known to lend a hand here.