All my characters have backstories...some small, some too large to put on the I.D.
But there is not a single characters that I create "just for fun". There has to be a reason for this hero (or villain) to exist.
Over the years these backstories have developed and little details have changed, but the overall story stays the same.
My main for example, Star Jewel (Energy/Energy Blaster), she was born with her powers but they only started manifesting around the age of 4.
And it wasn't until she was halfway through 16 when she actually (yet accidentally) used her powers. Which forced her to leave school and move to Paragon City. (No, she wasn't born there). She wasn't even registered as a hero a few years after moving there and being trained.
Her sister, Mystfury (Storm/Elec Defender), wasn't born with powers. She didn't even choose to have powers, they were forced on her by the Circle of Thorns when she got kidnapped by them while visiting her sister in Paragon City. Her backstory is dark and terrifying.
Then there are Emberflair (Fire/Psi Dominator) and Omegamax (SJ/EA Brute), both in their teens when they got their powers from magic space stones. Think Power Rangers meets Avengers Infinity War. There are 6 stones made of some exotic magic substance, each having a specific set of powers. Some big bad creature wants all 6 stones. Some old wizard from another planet tries to protect them. He loses 3 and brings the others to Earth. Emberflair and Omegamax find the wizard and the 3 stones. They merge with 2 and gain powers.
Their I.D.'s show nearly similar stories with only minor differences as they are told from their perspective.
Miss Unity (SS/WP Brute), similar to Captain America's origin, was created around WWII using science and tech. But she's not from the U.S., she is Europe's Super-Soldier. Working for the resistance during WWII she was nearly killed during a transport mission. Rescued by fellow resistance fighters and brought to a lab where she would become a super soldier voluntarily.
Lumitia (Ill/Rad Controller), alien princess, not of Earth, daughter of an emperor. Wanted to secretly study life on Earth but crashed instead. Earth's atmosphere changed her cell structure giving her the ability to manipulate light. She's an Illusion controller. Also, she's being "hunted" by the emperor's guards who need to take her home.
Novaspark (Peacebringer), daughter of Star Jewel and (unknown male), she inherited part of her mother's powers.
Dawnshade (Dark/Dark Dominator), orphan who was experimented on by a mad scientist.
And I could go on for a while, but this reply is already a whole lot longer than I planned. But you get the idea.