irdeggman said:
Really what I am trying to say is there is no surprise round in this scenario since everyone is "aware" of everyone else.
Yes. You are interpreting the phrase "aware of their opponents" to that of "aware of
the existance of their opponents" whereas I am intepreting it to mean "aware that someone actually is or might be an opponent". You are emphasizing the word "aware" whereas I am emphasizing the word "opponent". If one does not know that someone is an opponent, they are not aware of an opponent.
There could be 50 NPCs in a crowd and the PCs are aware of the existance of all 50 NPCs, but an enemy NPC in the crowd still gets a surprise round unless all of the PCs Spot that he is about to attack (or whatever). If none or only some of the PCs Spot the attack, then the Surprise round still occurs.
One doesn't say: "Well sure, he was in plain sight, so he cannot surprise you.". It's not about being visible. It's about being considered an opponent by the PCs.
It doesn't matter if the PCs are aware of the existance of the creature, they have to be aware or suspicious of the intent of the creature. Generally in a dungeon, PCs are suspicious of the intent of any creatures they see or hear. But, in the earlier example, they are not suspicious. The PCs are aware of the existance of the Doppleganger (thinking him a PC), but they are not aware that the Doppleganger is an opponent.
Since they are not aware that the Doppleganger is an opponent, that opponent gets surprise on them due to them being unaware. From the PCs perspective, there are no opponents there. Hence, they are unaware of any opponents.
This is an interpretive debate. Your interpretation does not allow for common sense situations like a PC walking up to an innkeeper he has known all of his life and suddenly stabbing him. The innkeeper is aware the PC is there, but is not expecting to be stabbed. Hence, the innkeeper is unaware of an opponent and unless he makes a Spot roll, he's surprised.
But, both interpretations are valid according to what is actually written in the PHB and the DMG. The examples in the books, however, discuss normal combat type situations where PCs are suspicious, not ones where they are not.