Black Widow

Black Widow is a perk for female player characters in Fallout 3 and Fallout: New Vegas.

Effects
In combat, you gain +10% damage against male opponents. Outside of combat, you'll sometimes have access to unique dialogue options when dealing with male character.

Fallout 3

 * You can talk Ronald Laren in the Nuka-Cola Challenge quest into a threesome. He then runs to the factory himself. He always seems to end up dead just inside the factory door if you do this, even if you accompany him all the way there.
 * You can talk Burke in Megaton into paying you double to do the job, or to give up on the bomb entirely.
 * You can talk Karl (during the Blood Ties quest) into giving you the password to Ian West's room.
 * You can talk The Mechanist into ending the battle with his nemesis, the AntAgonizer. You also get his costume.
 * You can talk Dukov out of his key without paying for it for during You Gotta Shoot 'Em in the Head.
 * You can convince Ramsey into selling slaves to you during Into the Pitt.
 * You can talk with Defender Morrill at the beginning of Operation Anchorage, so you can come through after the elevator, but that should not be a problem even if you don't have the Black Widow perk.
 * You can convince Wernher to give you 120 5.56mm rounds should you decide to side with the slaves during Free Labor.
 * You can use this perk on Sibley in the beginning of the Operation: Anchorage quest-line, where he will lead you to Protecter McGraw without the aggression. He still turns on you at the end, though.
 * You can use this perk on Paulson when you first meet him onboard Mothership Zeta''. He will tell you why he wants revenge.

Fallout: New Vegas

 * You can convince Chris Haversam that he is indeed human, thus allowing you to convince him to sabotage the rockets for the quest Come Fly With Me.
 * After asking for some work, you can persuade Swank to give you 100 caps to 'buy yourself something pretty'.
 * You can seduce Benny and get him to have sex with you when you first meet him, gaining a chance to kill him quietly in the night.
 * You can seduce Carlyle St. Clair III into having sex with you in a dumpster during Beyond the Beef, though you do not seem to actually have sex with Carlyle.
 * You can convince Old Ben to take up the escorting business again in Wang Dang Atomic Tango.
 * You can flirt with Jack at the Nellis Air Force Base during Young Hearts, as well as convince Janet to visit him at the Boomers camp.
 * A hooker named Dazzle in the courtyard of Gomorrah will have sex with you for 50 caps instead of 100.
 * You can convince Tyrone to give up the chemical ingredients in exchange for sex during the quest Don't Make a Beggar of Me.
 * After helping Dean with the Sierra Madre holograms you can immediately persuade him into doing his job with the fireworks display in Dead Money by claiming "a man with cold feet isn't somebody I'd share a bed with."
 * When talking to Your Brain during Old World Blues, you can flirt with it. It doesn't like that too much.
 * In Honest Hearts, you can tell Ricky when he offers sex that you will bring tweezers and a microscope.

Behind the scenes

 * Black Widow derives its name from the habit of female Latrodectus hesperus (black widow spiders) to cannibalize their mates during or after mating.

Gallery
Czarna Wdowa Чёрная вдова