Okay, so here's the thing: Some people need to learn to separate fantasy from reality. It boggles my mind how, say there are people who insist Digimon are real, or who confuse actors with characters on shows. I mean, I guess these things are endemic in any society that values fantasy and entertainment as highly as ours does. But it becomes a larger problem when you mix in things like role playing games -- when people can't separate their friends from their friends' characters.
I've been playing role playing games since I was 13 or so, and have gone so far to create not just one game of my own, but several over the years (the latest being partially available on this site). I've encountered all types over the years - from those who get too deeply into their games, to those who never really get into them at all.
Personally, I'm a player who creates an entire persona for a character I play. I understand their motivations, they have a backstory, and they have a unique way of doing things. Most importantly though, these characters are not me. They may have elements of me in them, but they are very different people.
Hence why I like playing them.
Currently, I am playing in a Dragonstar game set in a Firefly-like setting. In this game, I play the second in command of a Firefly class transport named "Vinny." Vinny is the ship's mouthpiece, face man, what have you. He's an extroverted, libertarian wiseguy who while having a moral center doesn't really have a regard for the law -- but most importantly -- Vinny is not me. Vinny even has a totally different voice and accent than I do, so it's not that hard to figure out when the character is talking, and when I'm talking.
This has not made things easy to differentiate for at least one other player though.
One of the other characters in the game was introduced with a back story that, from Vinny's point of view, is morally reprehensible. What this character did was on the top ten list of things you never do, and Vinny only hired the character... because it was rigged that way so the campaign could happen (storyline wise it was the only qualified person he could get -- and the person was incredibly qualified). In any case, it's not a situation where Vinny would ever consider being nice to this character.
It should be clear to anyone though that this is a personal conflict between fictional characters that in no way is based on anything done by a real person.
None of this is real. That, however, did not stop the person playing said character from going off at me last night during the middle of a session because my fictional character was mean to his fictional character. Seriously, it was absolutely mind boggling. This led to about a five minute diatribe about how he doesn't like it when my character is mean to his, and how he's told me (the player) that this bothered him before. I pointed out that it has nothing to do with him personally, and that this is just a situation between fictional people and not real on any level. This doesn't seem to have registered, but at least he dropped it.
This wasn't the first time I encountered this in a game. I remember back in high school when I was playing in an old Whitewolf Vampire game. The GM killed off the favorite NPC of one of the player's characters. The player freaked out and actually physically attacked the GM. This was more hilarious than anything else when it happened, but this was also high school and the player was probably only 15 at the time.
Everyone in the game I currently play in is in their 20s. At some point, one has to say "I'm an adult, and I'm going to act like one." If you reach your 20s and can't separate fiction from reality though, you really have bigger problems I suspect.