There are times when you'll be asked to make a roll. For example, a character in my game had been flaunting her Lustful trait. Then when she was on a sea voyage and a sailor came on to her, the player wanted her to resist. This seemed out of character, so I asked for an opposed roll of Lustful vs Chaste. Had neither trait won the roll (quite possible in Pendragon), she would have behaved according to free will, i.e. the player's choice. However, the Lustful was higher, and as you'd expect, won out. The character did not refuse the sailor (and she got a Lustful check).
Each religion has five traits which it considers the prime virtues.
The trait pairs are:
Chaste / Lustful
Energetic / Lazy
Forgiving / Vengeful
Generous / Selfish
Honest / Deceitful
Just / Arbitrary
Merciful / Cruel
Modest / Proud
Pious / Worldly
Prudent / Reckless
Temperate / Indulgent
Trusting / Suspicious
Valorous / Cowardly