Just as a preface i have read steelheart before but that was about 6-7 years ago when it came out, and i dont remember anything really about it.
As a little bit of a backstory for the backstory, it could be because im remember only a little bit but i think what steelheart does is out of fear and the first chapter can give you all the clues to that theory on its own if you think hard enough.
This is not a super far back childhood backstory, its set a couple months after the thing that gave the epics their powers.
Backstory: it had been only a few months after people started to become epics myself included, from what ive seen my powers are more powerful then others i have amazing powers and ive started growing bigger in every way basically. Before the calamity i was a average timid fearful man, fearful of what might happen and most importantly i fear death and i fear my time on this planet ending. That fear soon subsided when i realized how much strength i have. The only thing i need to be the strongest man is for people to fear me. Those who dont fear me can hurt me and i will stop at nothing to make the whole world fear me bit by bit so i can become immortal and never fear death agian.