Need help understanding fanfiction and derivative works

I publish illustrative scenarios prepared by my practice. All participants and conversations are fictional. The fictional posts are not posts by real users, accounts of client experiences, or reports of actual results.
Illustrative scenario prepared by my practice.
For informational purposes only. This is not legal advice. Laws vary by jurisdiction. Consult a qualified attorney for advice specific to your situation.
Hypothetical question

Looking for advice on a legal issue. Here's what happened.

fanfiction and derivative works. I've been dealing with this for about 4 weeks now and the situation isn't improving.

This involves software/code I developed over the past 25 months. I do have documentation proving my ownership and timeline.

Do I have a strong case? What should my next steps be?

Illustrative response

Just want to point out — the statute of limitations might be a factor here. In some states it's as short as 1-2 years. Don't sit on this too long.

Illustrative response

Not a lawyer, but I have direct experience with this.

The thing that gets people is having everything documented. I'd recommend keeping a detailed timeline instead.