In my upcoming game, another character will be playing an inveterate liar with middling popularity. New role players can't be expected to be as charming or devious as the most epic of heroes or villains, and we often need some mechanism to simulate that. This got me thinking about characters who are unknown but charming, without powers to sway their targets' minds or emotions (unlike Gambit, Purple Girl, etc.) Yes, I know Popularity is supposed to be a measure of both charisma and reputation, but I prefer to think of popularity solely as a force of authority from reputation:

• Use of positive or negative Popularity is asserting one's authority. When doing anything that might be construed as leading others, the Leadership talent grants a +1CS to Popularity FEATs
• Popularity doesn't cover all social encounters. The easiest method of convincing someone without using Popularity is with a rational argument. Unfortunately, this requires Reason enough on both sides to understand the problem. To formulate the argument, the PC must make a Reason FEAT against the intensity of the issue. The target must make a Reason FEAT at +1CS against the the same intensity (due to having the argument explained) to understand. But understanding does not guarantee action! Nor does starting a rational argument guarantee that both parties consider the argument (if this is in question, Popularity becomes useful)
  Example: Reed, college student, tries to convince his classmate, Victor, that the calculations for an experiment are flawed. The math is difficult, at Remarkable rank, but this only requires a green result for both young geniuses. Victor refuses to consider Reed's point and continues with his project using the flawed calculations. Had Reed decided to push the issue, he would have had to employ his Typical Popularity with an unfriendly target, just to get Victor to attempt the Reason FEAT
• Rational arguments are fine for scientists and some diplomats, but most diplomats and rogues (but I repeat myself) use a more creative art: Lying. You can use your Popularity to lie, just as normal; people just fall for "appeal to authority". Most successful grifters, however, aren't well known. Lying is difficult, involving a creative mind, ability to read the mark, and using a force of will or charisma to convince the mark.
  To successfully lie to an NPC, a PC must get a green success on all three of Reason, Intuition, and Psyche FEATs. The NPC resists with a FEAT check of their choice against the rank that the PC succeeded with (green is -1CS, yellow +0CS, red is +1CS). The column shifts for Popularity FEATs from page 18 apply to lying attempts. Each new piece of information contrary to the lie allows another Reason FEAT, and continued assertions of the lie from the liar allow additional Intuition or Psyche FEATs. ...Getting away with a lie long term is difficult.
  Example: The Hulk attempts to lie to Iron Man about who ate the last piece of pizza in the Avengers' Mansion refrigerator. The Hulk spends Karma to get a red success with his Poor Reason, but gets green results with his Typical Intuition and Remarkable Psyche. These results equal TY, PR, and EX intensities for Iron Man to resist. Iron Man uses his Incredible rank Reason to automatically succeed (see page 15 for automatic successes) against Hulk's Typical Reason result and sees through Hulk's story of "Loki stealing the pizza." Iron Man still has no proof that Loki didn't do it, but he's not ready to contact Thor, especially because he knows no one can prove a negative.

With this method, lying with low or no Popularity becomes mechanically cumbersome, which is contrary to the spirit of FASERIP, but I didn't want a way for someone with a mere high Psyche to duplicate simple mind control or one aspect of Popularity. Using this method does produce comics-like results too; Loki's lies are often discovered by the very observant or very rational. Very seldom does someone just disbelieve him with force of will, no matter how much they know he lies. Mephisto spins lies upon lies successfully, and almost always makes certain that the target will benefit in some way by believing the lie.

The lying thing is an awful lot of work. Personally, I prefer to keep things simple because lying isn't all that difficult in general.

PC tells a lie. Unless there is a reason to doubt him/her (such as an overly suspicious individual, evidence to the contrary of the lie told, or a history of lying from the PC known by the NPC being lied to, then the lie will be accepted. If there is some reason to be suspicious of the PC, then the NPC may make an Intuition FEAT to detect. I treat this like a Stealth attempt (per the Ultimate Powers Book), with the PC's lying rank determined by the way in which he or she wishes to tell the lie.

• Is it a well explained or possibly convoluted lie? If so, then the lie is based on Reason.
• Is it a lie of cunning, perhaps attempting to appeal to what the listener is expecting or wanting to hear? That would be a lie based on Intuition.
• Is it a blatant lie backed by sheer bravado and confidence? That's a lie based on Psyche.
• Is it a lie based on one's own reputation? Then that is a lie based on Popularity.

Once you have determined how the PC is attempting to lie, subtract the appropriate rank from the listener's Intuition score and they must make their Intuition FEAT based on that information.

• White FEAT: Failure to deduce the lie and acceptance of it as truth (for now, until something disproves the information).
• Green FEAT: is a minimal success, meaning that they doubt the lie being presented but are not entirely certain. Additional efforts may be made to lie to this individual again, perhaps after offering new "evidence" or additional lies. However, the already suspicious nature of the listener grants an automatic +1CS bonus to their Intuition rank after modification by the lie-teller's efforts.
• Yellow FEAT: Successfully disbelieve the lie, seeing through whatever intricate deception the liar has attempted to weave. The listener is not likely to believe the PC in the near future, at least, not unless they do something to prove themselves first.
• Red FEAT: The listener not only disbelieves the lie, but can easily point out flaws in the liar's logic or emotional appeals to grant others a +2CS bonus to their own attempts to disbelieve the lie. In addition, the listener has gained some insight into how the liar's mind works and will always be considered as "suspicious" when lies are being told, as well as always gaining a +2CS bonus themselves to see through those lies.

One roll is all you need. You just have to determine which one is the right one, and then adjust for the liar. Speaking of which... new talent:

Persuasion: The target is well spoken and gains a +1CS bonus to Popularity FEATs in general, as well as increasing their appropriate rank for lying as described above.