It is not new to have rules within which fictional characters work. Isaac Asimov developed the Three Laws because
he was tired of science fiction stories in the 1920s and 1930s in which the robots, like Frankenstein's creation, turned on their creators and became dangerous monsters. His laws/rules were simple, but there were enough
ambiguities in the Three Laws to make for interesting stories and character development.

Asimov's three laws of robotics are:

1. A robot may not injure a human being, or, through inaction, allow a human being to come to harm.

2. A robot must obey the orders given it by human beings except where such orders would conflict with the First Law.

3. A robot must protect its own existence as long as such protection does not conflict with the First or
Second Law.

Would you want to develop a framework or ground rules, maybe internal laws, for your characters to abide by? Then see what is possible.