Traits, as well as passions, are big part of the King Arthur Pendragon RPG. It truly makes it unique and quite honestly gives it a true legendary feel. Each knight can be seen acting against various vices and virtues in the stories. The biggest example that folks are familiar with of course is Lancelot. He is a chaste man, who failed his chaste roll and proceeded to critically succeed in checking his lust. We know he is chaste, when he is with Gwenevere, he is deeply ashamed to learned he slept with another, even though the other bewitched themselves to appear as Gwenevere.
There are times you will be challenged in a trait by circumstance in RP. Most of us may be used to simply acting in a way we deem the character would, but we're not driven by their passions, or we don't know the wiles that may affect them in the moment.
When a trait is challenged, or in circumstance of uncertainty on how one would act, trait rolling is encouraged. Here is a quick summary from the book on what the results indicate:
Critical Success | An experience check is normally gained, and the character acts strongly in accordance with the trait. |
Success | The character acts in accordance with the trait. The player may decide precisely what action ensues within that limitation. An experience check should be gained only if the action is somehow significant to the story or the character. |
Failure Roll | again, this time against the opposed trait. Success on this second roll means the character acts in accordance with that second trait. Failure indicates the player may choose freely how the character will act. No checks are given. |
Fumble | The opposite trait is checked, and the character immediately acts in accordance with the checked trait. |
We all want to look good, no doubt about it, but failure is sometimes the better story. We mostly don't remember the one time that we overcame the obstacle on the first try. The story moves along, we forget that one dice roll to achieve that. But when we fail and have to figure out an amends, deal with the consequences, and finally move on, the story truly develops from that. My greatest stories from Mu*ing generally start with one failed roll, and a series of unfortunate events and continue until I found myself on the right path again. We want to win, but give failure a chance.