Charisma/Fallout: New Vegas

Charisma is one of the seven primary statistics in the SPECIAL system.

Gameplay
Charisma in New Vegas modifies Barter, Speech and Companion Nerve. Companion Nerve gives each companion in the party +5% to their damage and armor, up to a maximum of +50% at 10 Charisma. Regardless of Barter or Speech level, some interactions will not be available with a too low Charisma.

Permanent

 * Charisma Implant available at the New Vegas medical clinic (+1)
 * Intense Training perk (+1)
 * Completing the quest The Apocalypse or The End will allow raising any one primary statistic by 1.

Temporary

 * Alcohol (effects do not stack)
 * Absinthe, beer, Jake Juice, scotch, vodka, whiskey, wine (+1 - +3 depending on Survival skill)
 * Irradiated Beer, irradiated scotch, irradiated whiskey (+1 - +3 depending on Survival skill)
 * Large wasteland tequila, wasteland tequila (+1 - +3 depending on Survival skill)
 * Moonshine (+2)
 * Armor and clothing
 * Bounty hunter duster, regulator duster, sexy sleepwear, sheriff's duster, sleepwear (+1)
 * T-51b power helmet, Eulogy Jones' Hat (+1)
 * General Oliver's uniform (+2)
 * Vera's outfit (+1)
 * Dr. Mobius' scrubs (+1)
 * Armor of the 87th Tribe, Ulysses' Duster, Elite Riot Gear (+1)
 * Chems
 * Mentats (+1)
 * Ant Queen Pheromones (+3)
 * Party Time Mentats (+5)
 * Traits
 * Claustrophobia (+1 while outdoors, but -1 indoors)
 * Early Bird (+2 between 6am and 12pm, but -1 between 6pm and 6am)
 * Meat of Champions perk (+1 for 60 seconds after eating a corpse.)
 * "Mood Light" (+2 for 12 hours or until the player uses the "Smart Lights")

Decreasing

 * Remnants power helmet, Remnants Tesla helmet, Gannon family Tesla helmet (-1)