Affiliate Marketing Secrets

Are your stories mostly about you in fantasy lives or do you write mostly about what you think would work commercially. I mostly write what interests me which is mostly romance or sci fi usually combined. But I get that it could have a small niche market if I wanted to sell one of my finished books. I’m usually the main character Somtimes I use my real name sometimes I give myself another.
Is it better to use made up characters? Do you know of any writers who openly admit to writing themselves into their stories?

I am writing a short story about an orphan. His parents were murdered on the day the sun and the moon lied immobilized in which everything was frozen (earth sun and moon). He goes to an orphanage and fin his best friend, Well afterwords, the main characters brother gets murdered (thirteen years later) and the murderer is his best friend. I like how I outlined things but I have one gigantic writers block. I want the best friend to be the murderer of the family and I would like it to be affiliated with the immobilized moon and sun. I thought of having the dad as the president of an organization that deals with the moon and the sun but I just don’t know how that would fit together. I would really appreciate it if you had any ideas because this has been bothering me for quite some time. I’d like something good and would make someone think oh my god! Please reply as soon as possible. Thank you 🙂