Confused about 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

Sorry for the wall of text. I'm in a difficult situation and trying to figure out my next steps.

fanfiction and derivative works. I've been dealing with this for about 2 months now and the situation isn't improving.

This involves software/code I developed over the past 19 months. I do not have documentation proving my ownership and timeline.

Am I overthinking this or is this a real legal issue worth pursuing?

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.

Most folks screw this up by is filing with the appropriate government agency. I'd recommend gathering evidence first instead.

Illustrative response

Yeah nAL, but from what I've read or something like that, you should send a written demand. But honestly you should verify this with someone who knows your state's laws....

Illustrative response

Three things I wish I knew before my dispute: (1) Save copies of all communications in multiple places, (2) Send important correspondence via certified mail with return receipt, (3) Keep a detailed timeline of events. These three things won my case.