I don't always DM, but when I do, I prefer NPCs to be NPCs.
And the definition of a NPC vs. a DMPC is.....? Or in your case, a NPC that is a NPC is....?
What qualifies as a DMPC?
Player perception: does the NPC fulfill the role the players perceive the NPC to have, or exceed it? If he fulfills it, then he is an NPC. If he exceeds it, then he is a DMPC.
I don't even know what this means.
I've had NPCs with the group that have been; excellent duelists, supreme magicksters, excellent rage-barbarians, little crystal globes of light that heal people, regenerative kobold that can't die, not to mention others that are slipping my memory at the moment. Some have been over level, some same level, some below level.
For example, the players may be looking for a guide who is also an accomplished archer. So long as the NPC fulfills the roles of guide and accomplished archer, then, in my experience, players view the NPC positively. On the other hand, if the NPC is also an accomplished trapsmith (thus overreaching on the PC rogue), or his archery skill is exceptional (thus becoming the party's primary tactic), then, again, in my experience, players view the NPC negatively and refer to him as a DMPC.
That last line right there, that is all I know of DMPCs.
NPCs = good
DMPCs = bad
Without any idea where the line is drawn.
You say "expectations" but that is a useless definition (I'm sad to say). It can't really be predicted or quantified. It is like my asking "what is the definition of a cheese casserole vs. mac and cheese" and you replied "you'll know when people tell you if it tastes good or bad."
I'm sorry to say that I need more.
My example is combat and exploration-focused and can easily be extrapolated into the other areas of the game: interaction, logistics, problem-solving, and so on.
So, in your example, the NPC who is guiding and can shoot = good
The NPC who can trapsmith = bad?
And its bad because the NPC is treading on the rogue's toes? What?
One NPC I introduced was a kobold (part of the list above) that was trapped in a gelatinous cube. As I recall he had been given regenerative powers somehow (it has been a while and I forget) and was being fed to the cube in order to increase its size. The party eventually killed the cube, freed the kobold and then insisted he come with them.
Later they tried throwing him down hallways they thought were trapped, because the kobold was immortal and could not die from the traps effects. So, at this time he became "the party's primary tactic." Is that what qualifies him to be a DMPC? Not anything I would actually do, just physically being tossed down the hall? He could not talk (sit mute in a bag of holding until needed) and he's still an DMPC for that quality?
There are also DMs out there who are just obnoxious even when their NPCs do meet player expectations. These DMs I view as being problematic overall and not worth gaming with regardless of whether their NPCs meet or exceed my expectations.
Right, but being obnoxious isn't the defining quality of a DMPC. It is a defining quality of poor DMing skills, or of poor NPCs in general but it fails to describe why a DMPC might be suck. If that casserole is on fire, I don't blame the casserole (the cheese and mac) I blame the oven for setting it on fire - a different issue entirely.
OR is the qualification of DMPC = bad, ALWAYS. Meaning you cannot be a good DMPC, it goes contrary to the description of what it is. Like
Good Murder.
Killing can sometimes be justified but
murder is always bad.
So only bad DMs can run DMPCs. If it is that is fine, but then I think we solved the thread. We could then start another called, "How do you feel about NPCs?"