So spoke Tyler Durden, while assembling his army of terror. (In my interpretation, because he couldn't just own up to liking Marla and hating his job, but that's neither here nor there.)
It's often quoted about PCs, especially in old school games.
But I have to disagree.
The PCs are unique. They are special.
Why do I say so?
1 : distinguished by some unusual quality; especially : being in some way superior
2 : held in particular esteem
3 a : readily distinguishable from others of the same category : unique
b : of, relating to, or constituting a species : specific
4 : being other than the usual : additional, extra
5 : designed for a particular purpose or occasion "
1: being the only one : sole
2 a : being without a like or equal : unequaled
2 b : distinctively characteristic : peculiar
3 : unusual
I think a lot of those fit PCs.
They are ones you play. The world is full of NPCs. You generally aren't playing out their exploits, tracking their growth, calculating their encumbrance, and rolling for their actions. The ones you care about are the PCs. Obvious, sure, but it's important. It's part of what makes them special - they're different from the NPCs/GMPCs/whatever you call them in the rest of the world.
They are the interesting folks. Do you play out the lives of boring people doing ordinary things and then let them hear from the GM about the cool NPCs doing the cool adventures? No? Too Mary Sue, probably? The players get to run the people who do the things worth doing, or you're left wondering, why not play the others?
Generally you're playing interesting folks doing interesting things. Or not-so-interesting folks doing interesting things. But they're worth paying attention to.
The game does revolve around them. You show up on Sunday (at least on my schedule) and play these guys, out of everyone in the world. What happens to them and what they do is where the fun comes from in the game. The world doesn't revolve around them (although it might, depending on the campaign and game), but play does.
It's even perfectly okay in some game systems for the PCs to use different rules. Sometimes it's a matter of resolution (early D&D doesn't stat out monsters and PCs to the same degree) or actually different rules (Check how GURPS influence rolls work on PCs - you can make NPCs do stuff, but merely penalize PCs for acting against what the dice dictate.)
You generally get each guy once. Unique - if your knight Fred the Fearless dies, it's generally not considered okay to just make a new guy named Fred the Fearless with the same stats. They aren't interchangeable like chess pawns (or even chess kings). If Fred the Fearless dies irrevocably, his experiences die with him, even if the player can remember them. His next guy can't claim to have done the stuff his previous guy did. Even if you do allow people to just, say, put a "II" or "Jr." next to the guy's name and run him, it's still a different character.
Okay, so if say they're special . . .
Does this mean you fudge rolls for them? No, that's a different decision. "Special" does not mean "given special privileges" or "get the rules changed for them." That may be a valid decision in some games, but it's not the same decision. In some games, yeah, the world really does work differently for PCs than for NPCs. In others, the rules are more-or-less the same but main contain some differences (D&D has different attack matrices for monsters vs. classed PCs, and monsters don't generally come with stats or stat modifiers). Some games - Dying Earth for one - is especially brutal in this regard, since NPCs and other PCs can force you to play your PC differently based on their and your rolls.
Does this mean the world is play-balanced for them at all levels of play? No, that's also a different decision. "Special" and "unique" do not need to mean "provided a consistent challenge." Again, a different decision. It's a choice about how you structure the campaign world and the play within it, not a judgment on the PCs per se.
Do I need to make up a 10-page background for them? No, of course not. And "special" and "unique" doesn't imply a huge background. Snowflakes don't need to have a 10-page background to be unique and special. You can whip a guy up in one minute and play him the next minute and he's still special, even if his background is "Fred the Second, little brother of Fred the Fearless, takes up his brother's gear and heads to the dungeon to avenge his brother." Done. Still special. You'll still remember the guy if he accomplishes anything interesting, even if parts of his character and specific details fade away.
So I'm just saying . . . In my opinion, the "beautiful and unique snowflake" thing is a bit overused and it's a fairly inaccurate characterization.
Really, what people want to say, in my experience, is "In old school games, PCs don't deserve special consideration just for being PCs." I think that's true, but they are beautiful and unique snowflakes all the same. They are all different, they're pretty delicate, and you treasure them until they melt, which happens depressingly often if you play my sorts of games.