During my AD&D game last night, the magic-user was using Detect Evil on a number of objects the party had found within the Citadel of Chaos. While using the spell, which lasts 5 rounds per level, the magic-user decided to sweep the rest of the party, as it contained two relatively new characters. He discovered that the "fighter" who recently joined them is evil.
"Don't ask, don't tell, motherfucker!" the assassin's player exclaimed.(Out of character, naturally) This, by the way, is one of the funniest things I have heard at my gaming table in recent memory. (Though perhaps it was one of those "you had to be there" moments...)
It has been a well known fact that one of the party members is an evil elf assassin disguised as an elderly human fighter. The magic-user, whose player is known for advocating party harmony, has decided to keep the information to himself. (That is, the whole group knows, but in-character, only the magic-user knows, and all he knows is that the "old codger" is evil.)
I make it no secret that I am not a fan of AD&D's alignment system. In fact, of all alignment systems, the only two I really like are Palladium's, as it clearly spells out what is expected of each alignment within the game's framework, and basic D&D, since good and evil have nothing to do with it. (Though many writers of older D&D material seemed to just use Law and Chaos as synonyms for Good and Evil...) In my campaign I have largely ignored alignment, but until now we haven't had characters of opposite alignment in the same party.
Since only one character knows the truth, and he is not of a character class that has restrictions on what alignments he may associate with, it appears that these characters might actually be able to coexist. The assassin has acted in a more or less neutral fashion, as he wants to maintain his disguise. From what I understand, he is evil because of his profession, but doesn't intentionally screw other people over for no reason. I consider the next several sessions to be an experiment on the vestigial nature of the alignment system.
Interestingly enough, I'm told that the original purpose of alignment, dating way back to Chainmail methinks, was simply to indicate which types of creatures could be in the same army.
Now...what about you, my dear readers? Have you had alignment coexistence in your games?