Every character has a backstory. Even if the writer doesn't reveal it, the backstory is there. These backstories are valuable in developing a character and understanding them.
I was in the process of writing a romance story. It is called The Cost of Second Chances and can be found on Wattpad -
https://www.wattpad.com/story/2092232.... Someone reading as I was working on the first draft asked sevreral questions about Marcus and how he met Hannah. The more questions she asked, the more I realized I had to dive into that backstory. That resulted in Pure Obsession -
https://www.wattpad.com/story/2092236....
Then that had me wondering even more about the evil Marcus. That led to a short story -
https://writerrebeccagraf.com/writing....
Backstories are important.
Backstories are fun.
If you are a writer, enjoy exploring the backstory. If you are a reader, enjoy them. Learn the depths of a character and watch them become even more alive.