I find myself prone to creating GMPCs.
For the unfamiliar, a GMPC is an NPC that the GM has a special fondness for, much like a "Mary Sue" in fiction. They are often overpowered, have plot armour, a key role in the story, and might be played as smug, superior, mysterious, or all three. A definite sign of a GMPC is that the GM expects the group to react favourably to it and takes offense otherwise. GMPCs can result from a GM secretly wishing to play this character, but not having the opportunity as a player.
Of course, I don't like to admit that my NPCs are Mary Sues but indeed I have at least one NPC that evolved from a player-character concept to a fully-fledged NPC. This has happened that I realised that the idea for the guy was very powerful, but also that I will never be able to play him properly, as he's too incompatible.
The problems and how I am mitigating them:
- My GMPC is flawless, but in a way that he is a very powerful entity with a few major flaws, that can be exploited once discovered, but that would be very hard.
- My GMPC is extremely powerful in comparison to the PCs, but they are never going to be directly confronting him.
- My GMPC is invincible, but it's because the plot does not equip the players with the means to destroy him (they could get them, but only by actively seeking), he is instead supposed to be a force of nature.
- My GMPC is not there as a central part of the story, but a meddler, who comes in, has his own separate agenda and disappears. The players can strike a deal with him or oppose him, but they can very well avoid him and still emerge victorious.
- My GMPC acts all smug and mysterious, because he is a self-important jerk. He is usually kind to the PCs as long as it keeps him entertained. He will not kill them for telling him off and he actually would very much like to be surprised (think of a thousand-year old elf, who has really seen it all, and meddles with humans to make his life more interesting).
- Well, I would indeed like my GMPC to see the light of day and that's the only way I can think of to make that happen.
The GMPC will not accompany the group. This is not a person who would "hang out", but rather pursue his own business in the same area—so the party will stumble upon him from time to time. He might help them if they request it (or lure them into a trap if they annoy him), but he's not supposed to take part in the adventure. If the party was The Fellowship Of The Ring, say, this guy would be a wizard trying to harness the power of a volcano. He doesn't give a **** if they throw some ring inside, but if they lead the orcs away, that makes his life easier, right?
What should I do to have this kind of a character in the campaign without spoiling the fun?
What are the common pitfalls that I failed to recognise?