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 characters.

Fallout 3

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

Fallout: New Vegas

 * One can convince Chris Haversam that he is indeed human, thus allowing the Courier to convince him to sabotage the rockets for the quest Come Fly With Me.
 * After asking for some work, one can persuade Swank to give them 100 caps to "buy yourself something pretty."
 * One can seduce Benny and get him to sleep with them when he is first met, gaining a chance to kill him quietly in the night.
 * One can seduce Carlyle St. Clair III into having sex with them in a dumpster during Beyond the Beef.
 * One can convince Old Ben to take up the escorting business again in Wang Dang Atomic Tango.
 * When Rose of Sharon Cassidy comments that the Mojave is not a place for 'soft living or soft men', one can joke that men don't stay soft around them for long.
 * One can flirt with Jack at the Nellis Air Force Base during Young Hearts, as well as convince Janet to visit him.
 * A hooker named Dazzle in the courtyard of Gomorrah will have sex with the Courier for fifty caps instead of 100.
 * One 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 Domino with the Sierra Madre holograms, one 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 the Courier's brain during the quest Old World Blues, one can flirt with it. It doesn't like that too much.
 * In Honest Hearts, one can tell Ricky when he offers sex that they 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. Idiomatically, a black widow is a woman who kills her lover(s), usually in a serial fashion.

Schwarze Witwe Viuda Negra Czarna Wdowa Чёрная вдова (способность)