I had an interesting experience recently which playing Dungeons and Dragons. The other players were mainly beginners and the party had just discovered some treasure. To make a long story short my character found several magical rings and took them all. Another player demanded that they be shared and when I decline his character drew a weapon and insisted at swordpoint. The situation was quite awkward and left many of the players wondering. How do you manage that type of conflict at the role playing table?
Even as I write this account the essential difficulty of the situation becomes clear. The players each have a character and they act out what the character is doing. So Mike Fischer isn't taking the magic rings, it's Ashraf the Illusionist. And Joe Smith isn't pulling a sword and demanding they be shared, it's Krunk the Dwarf. Some players might argue that any behaviour is acceptable if it fits what the fictional character would be prone to do. If your character is a thief then she could and likely should steal from the other members of the party. If your character has a short temper then you should act that out.
I think the role playing realism approach has some merit. I like role playing and being true to your character makes for some unpredictable and exciting games. Further, you could argue that role playing an unusual or complex personality is a real achievement in terms of your own creativity and acting skills.
In the end I decided that while you can justify inter-party conflict as role playing that doesn't make it fun for me personally. Granted it's not "against the rules," and may even be supported by the rules. Nevertheless it just wasn't fun. Specifically: it wasn't fun for me. So how does this apply to gaming in general, or anyone else in the world?
If you're assembling a gaming group or starting out games it may be a good idea to talk about what the player's goals are. You could ask whether everyone is comfortable with aggressive styles of playing, with triumphant yells or competitive comments. If you're playing with children you might take a more directive role and help them grow into good social gamers. I've encountered skilled teen players who are shunned because their aggressive style is just too irritating for the other people in the group.
The role players may want to discuss the levels of realistic violence and drama they're comfortable with. One player may feel that graphic descriptions of combat are uncomfortable. Another player may be unwilling to play in a game in which the characters can turn on one another. Or all the players may agree that the game is a free-for-all and that any level of mayhem is acceptable.
In the end I decided that whatever the arguments for or against inter-party conflict were, for my purposes it just wasn't fun. At age 45 any free time is pretty precious and there's just no point in sitting through a game that's not enjoyable. At the same time I resolved not to antagonize the other player by appearing as though I wasn't sharing. His time is just as valuable as mine of course and in the end the point of the game is to have fun as a group- otherwise you'd just be playing solitaire.