I think I found a really clever solution for an NPC who always follows the PC everywhere: Just make the NPC a part of the PC. (You are allowed to say that people are parts of other things, including people. It’s gross. But it comes in handy.) I like this a lot better than I like writing a rule for moving that NPC around every time the PC moves.
As it turns out, the block-taking-a-person “I don’t suppose the NPC will care for that” rule supersedes the block-taking-a-part “That seems to be a part of yourself” rule, which works great for me.
I anticipate, though, that there are other default responses for parts of things that might be really confusing if they show up describing a person. Can you think of any? Or, can you think of any other problems that might result from attaching an NPC to the PC?