Fallout: New Vegas Reputation

Overview
Reputation in Fallout: New Vegas is a measurement of how the different factions in the Mojave Wasteland perceive your character. It is affected by positive and negative deeds that affect the faction in question, such as completing quests or killing members, respectively.

Reputation is separated into two categories: Fame and Infamy. Fame is positive and infamy is negative. Both types of reputation are tracked separately, the combination of which determines your reputation with any given faction. The benefits and drawbacks of any given reputation depend on the group itself. You may receive discounts with merchants, provoke attacks from hired thugs, or simply be treated differently.

Certain types of clothing or armor carry a faction affiliation (e.g. NCR armor), allowing you to impersonate a member of the faction the clothing belongs to.

While the armor is equipped, the player's reputation with certain factions is masked to "none" and hostility is set to whatever hostility (or non-hostility) exists between various factions. You become an anonymous member of that faction with no reputation history (neither fame nor infamy) even if you previously acted in that disguise and gained a reputation. Scripted Fame and Infamy are still applied to your true reputation scores. The temporary mask from disguise typically reduces any penalty until the disguise is reset (by taking it off and then putting it back on). Some characters in a faction (including officers, security guards, and dogs) can see through disguises and react to your true reputation.
 * For example, if you put on NCR armor, any accumulated reputation with the Legion and the NCR will be masked and both the Legion and NCR will disappear from the faction list, as if you had never acquired any reputation with them at all (not even Neutral), as if you had never met. However, since the Legion is normally hostile to the NCR, that hostility is not set and Legion units become hostile as if you were an NCR member. If she is in your party, Veronica Santangelo will probably immediately speak with you and warn you against continued hostility against the Brotherhood of Steel.
 * For example, if you are Idolized by the NCR and would normally become a Good Natured Rascal after test-firing ARCHIMEDES I and II at HELIOS One.
 * If you wore NCR armor before test-firing, your NCR reputation disappears from the list, as normal.
 * After test-firing, the scripted infamy gain drops your reputation to Shunned.
 * When you take off the NCR armor, your true reputation is revealed as Good Natured Rascal (as if you had test-fired ARCHIMEDES without the disguise).
 * If you then put on the armor again, your reputation is again masked and disappears from the list, as if you hadn't test-fired ARCHIMEDES.
 * If an enemy is already hostile to you, killing them does not add infamy. Therefore, you can, for example, put on NCR armor to make the Legion hostile, kill Legion soldiers, then take it off later and not be Vilified by the Legion.
 * They may be non-hostile prior, but if they spot you they will turn hostile if they would normally be hostile to you without your armor.
 * Units that couldn't see through your disguise also become hostile.
 * Depending on your disguise, the reverse could happen. For example, if a Courier has a Neutral reputation with the Legion and sneaks about a Legion camp with NCR armor, common Legion soldiers who cannot see through the disguise will be hostile and show as red on the compass. However, Legion Mongrels can see through the disguise and will not be initially set to hostile because they would not normally be hostile to the un-disguised Courier.

Reputation
Fame and Infamy (denoted 1 and 0 in the console) are earned by doing helpful or harmful deeds, respectively, to the faction. The combined effects of the two scales result in an overall reputation that is either positive, neutral, or negative. In the table below, these are colored green, black, and red respectively.

With a few exceptions, Fame and Infamy will only increase, meaning any positive or negative reputation with a given faction cannot be removed, only offset by a larger Fame or Infamy value. In other words, while it's possible to move from 'Hated' to 'Sneering Punk', then 'Unpredictable', then 'Dark Hero' by doing more and more good deeds while avoiding bad ones, there is no permanent way to move from 'Hated' back to 'Neutral' or from 'Hated' to 'Idolized.' Similarly, once a reputation of 'Wild Child' is earned, there's no ability to change it at all. Only three exceptions exist. The NCR and Caesar's Legion, two of the game's primary factions, will grant a one-time offer of amnesty for past misdeeds, resetting Infamy to zero while leaving Fame at its current level. Once this offer is given, any Infamy gained after that point is permanent. James Garret can be paid to start rumors in Freeside that affect your reputation with the town. There is no limit to how much this can be done.

Using faction armor, it is possible to gain a higher reputation than would be possible. Equip the armor of the faction you are trying to work with to reset your reputation to neutral. Then complete quests and earn fame which will increase from neutral and go up, but only so long as you wear that faction's armor.

For specific low-level range values for various factions, see the Talk Page.

Faction reputation
Each faction has a disguise which alters your reputation among other factions.

With the exception of the White Glove Society, Great Khans and Powder Gangers in Vault 19 all factions will attack you with a negative reputation. Additionally, Powder Gangers outside of the NCR Correctional Facility and the Powder Ganger Camp South would originally attack you even with a neutral reputation if you got too close to one, but this has been corrected in the latest patch to the game.

Factions provide the following benefits/consequences with adequate reputation:

Quest scripts themselves rarely grant infamy towards factions, but there are a few which do:
 * Failing Beware the Wrath of Caesar! gains infamy with the Legion and turns them hostile. Reporting to Colonel Moore or Mr. House that the Omertas have been dealt with in For the Republic, Part 2 or in The House Always Wins, respectively, or by completing both Wild Card: Change in Management and Wild Card: Side Bets, will cause the quest to fail, as will killing enough Legion troops (though this is a moot point since they will be hostile anyway).
 * Failing Don't Tread on the Bear! will gain NCR infamy, the amount and exact consequences depending on how it is failed. Reporting to Caesar that the White Gloves will or will not ally with him in Render Unto Caesar will cause infamy with the NCR and turn them hostile. Working with Yes Man or House will fail the quest, but the Infamy gain will be trivial and the NCR will remain friendly. However, all active NCR quests will be immediately failed, and it will be impossible to accept further quests from them.
 * Completing Back in Your Own Backyard in any way will result in Legion infamy, although this infamy is not enough to lower your reputation by one level on its own.
 * After completing How Little We Know by siding with Cachino and speaking to Caesar, you will be warned that further crimes against the Legion warrant death. Completing Restoring Hope, Oh My Papa by breaking up the Legion alliance, or I Put a Spell on You by siding with the NCR and speaking to Caesar after this warning OR speaking to Caesar again after failing to confess all crimes will result in Legion infamy and the Legion permanently going hostile. Note that certain scripts, such as Caesar's dialogue on House's death, will override his 'warning' dialogues.
 * Activating the self-destruct sequence in Hidden Valley gives you 100 infamy points with the Brotherhood.
 * Activating the Archimedes I and use it against the NCR trooper in That Lucky Old Sun quest will result in a large amount of NCR infamy.
 * Completing Ghost Town Gunfight will always grant enough Powder Ganger infamy to lower your reputation by one level. Killing any Powder Gangers during the quest will further increase your infamy.
 * Completing Beyond the Beef by snitching on the White Glove Society to Heck Gunderson results in White Glove infamy.
 * Telling Marjorie that you "eat people, too" will result in the White Glove Society infamy.

Towns reputation
A town's reputation determines your treatment by the townsfolk. Unlike factions, you cannot alter a town's reputation with faction armor. Towns will never be permanently hostile to the player; leaving the town for three days and returning should remove any hostility. Note: Script for Primm reputation exists within the game, but is not used. A mod exists for PC users to activate Primm reputation.

A positive reputation may yield positive dialogue, discounts from vendors, and even free gifts from wandering citizens. A negative reputation may result in negative attitudes by the citizens and higher prices when trading.

Specific consequences of reputation within towns include:

Scripted instances of town infamy include:
 * Lying to Lindsay about Mr. Cuddles results in Boomers infamy, regardless of whether you pass the Speech check.
 * Walking off during Pete's story in the Nellis Boomer Museum or condescendingly responding to his answers to your questions will result in Boomers infamy.
 * Completing Run Goodsprings Run will always lower your Reputation by one level in Goodsprings; killing townsfolk yourself results in further infamy.
 * Completing Beyond the Beef in a way which results in Heck Gunderson blockading food to the Strip will result in Strip infamy. Generally, this infamy would be garnered by tattling on the White Gloves and failing to pass the following Speech check.
 * Completing How Little We Know by siding with Big Sal will lower your Strip reputation by one level.

Bugs

 * A Negative Reputation With the NCR—They give you 3 days to remove your negative status. If you wait 24 hours in the same spot after they've warned you, interacting in dialogue with them each day, you may find their dead bodies randomly in front of you when judgement day comes. How they were killed is unknown.
 * A Negative Reputation With the NCR—NCR Rangers have been spotted inside Vault 34 during the quest "Et Tumor, Brute?" possibly attempting to warn you about your bad reputation (or killing you). They'll engage in a battle with the feral ghouls of the vault before attempting to interact with you.
 * Encountered a bug where Legion were hostile no matter what even though reputation with them was either liked or idolized. DID NOT have Boone as a companion or even have him recruited, nor was any faction armor worn. Work around: thankfully this reset after completing Ring-a-Ding-Ding!, although dogs sometimes still turn hostile for no reason forcing the player to sneak attack them when this happens to maintain reputation. This may have been possibly caused by previously wearing another faction's armor and upon removing it the disguise was not properly removed which is another known bug.
 * When wearing faction armor, reputation with certain factions changes, Eg. When liked by the NCR without NCR faction armor it is fine but when wearing NCR faction armor, reputation goes down to neutral from liked.
 * When you put on faction armor, the game masks your reputation. If while wearing the armor, you put it away into a container without first taking it off, the game does not unmask your reputation and can cause some of it to disappear (i.e., the faction does not show on the Reputations screen). Putting on the armor of the same faction, and taking it off, will cause the scripts to run and should restore your reputation properly.