After thinking about it for a while, I think I can finally answer this.
I don’t feel like it’s my place to tell you that you can’t do it, but I can admit that I’d feel uncomfortable with someone continuing this story. It’s not that I’m possessive over the character, since, as you mentioned, I don’t own JTK. But the story of Fear Me is a different matter. I have to admit that I am protective of the story itself, including the plot, the characters exclusive to the visual novel, and even my design of Jeff.
Once again, I’m sorry that so many people are hoping for a sequel and that I can’t give you one, at least for now. I’ve said many times that I’m not planning a sequel or DLC because I’m not currently working on one. Right now, I’m focused on my original projects, mainly because I don’t want to depend on this fangame or keep squeezing content out of it until there’s nothing left.
If you’re patient, I might eventually make a continuation. I can’t promise anything, because it would be unfair to give you hope and then not be able to deliver. But I can assure you that it is something I’ve considered, and maybe someday in the future, I will.