From a newsgroup post dated December 16, 2009:

And here’s another idea I didn’t need — suppose there’s a secret government project that’s opened portals to other realities, maybe on purpose, maybe accidentally. The other realities are inhabited by humans, or at least creatures indistinguishable from humans, who appear to have a lower tech level than ours — or at least a different tech level.

Our guys want to know what’s going on in these other worlds, but they don’t want to interfere, they don’t want to start any wars, and they’re not ready to make any direct, open contact; for one thing, they want to know who they should contact. Who are the good guys over there? Who are the bad guys? Who’s gonna be trouble?

These are other realities — are the laws of physics the same? Close enough for humans to exist, but is everything the same?

Someone gets sent in to scout. This isn’t something you can trust to civilian contractors, and it’s not really the military’s job, and we aren’t ready for the State Department, so the CIA gets the call.

So we have a 21st-century CIA agent trying to blend in in a fantasy world…