Typically used with: Self-Control.
In short: abstain. Those who strengthen the Virtue skill are effectively able to resist temptation. While it doesn't necessarily represent a strong moral code, it does infer a character has strong force of will over their impulses. Virtuous characters are prudent. They're able to reign in their natural reactions when provoked, solicited, tempted, or coaxed.
You must make a Virtue check when a situation calls for you to show a little control. Sure, that priceless urn looks tempting, but should you really take it? Yeah, you may have your mother's killer at gunpoint, but should you really pull the trigger? Even though the queen just insulted your husband, is it wise to slap her? Any time your better judgement needs to interject, you need to make a Virtue check. The more tantalizing the thing is, the higher the DL.
If most people could say no, it's DL 10. If you need to think about it, it's DL 15. Anything very enticing is at least DL 20. If you'd gouge out your own eyes to make it happen, it's DL 30 or more.
If you have a predisposition to desire the temptation (e.g. a kleptomaniac vs. a wallet, a recovering alcoholic vs. a drink), you take a −5 penalty to the Virtue check.
A creature can chat you up for a few minutes and then offer you an enticing reward in exchange for your cooperation. If the reward is something you'd want, they make a Seduce check while you make a Virtue check. If your result meets or exceeds theirs, you have no problem turning down their offer. If your result is lowest, you give into temptation and cooperate (despite your better judgement). An ally may be able to turn you away from a bad decision with a good Leadership roll.
During combat, an opponent can throw insults your way in an attempt to enrage you to the point that you start making careless mistakes. They roll a Taunt check. You roll a Virtue check. If your result meets or exceeds theirs, you maintain composure. If your result is lowest, your anger overwhelms you and you take a −2 penalty to all rolls during the encounter.
You must also make a Virtue check when another character uses Seduce or Taunt to draw your attention. If you meet or exceed the other character's check, you remain alert. If your result is lowest, you gain the distracted condition. If you roll a Critical Failure, you gain the wide-eyed condition.
If the opponent rolls Seduce: the effect lasts up to a minute, as long as they keep up their alluring behavior. If the creature rolls Taunt: the effects last for a single round. During this time, if something catches your attention and interrupts the opponent's attempt, like being attacked or being distracted by someone else, the effects end.
Many compulsory spells can be averted with a Virtue check, for instance Befriend and Pheromones. In this case, you may add any points in Magic Defense to this roll. The mage makes a Casting Roll. You make a Virtue check. If your result meets or exceeds the Casting Roll, you elude the effects of the spell.