[[quoteright:148:http://static.tvtropes.org/pmwiki/pub/images/affinity-1573228737-L_1573.jpeg]]
''Affinity'' is a novel by British author Sarah Waters, first published in 1999. It explores a dark period in the lonely life of Margaret Prior, a youngish spinster from a wealthy English family. Margaret begins visiting a women's prison as a means of escaping her own ennui and in the hopes of being a positive role model for the inmates. There she meets a young prisoner, Selina, with whom she becomes infatuated. But it is unclear what the mysterious inmate's motives are...

A [[http://www.imdb.com/title/tt1116182/ film adaptation]] followed in 2008.

!!Examples:

* AdaptationalAttractiveness: Margaret.
* AnachronicOrder: In the book, entries from Margaret's diary are mixed with entries from Selina's; the latter predate the former by about two years.
* {{Angst}}
* [[spoiler: BatmanGambit: Selina and Ruth run one.]]
* [[spoiler: BitchInSheepsClothing: Again, both Selina and Ruth Vigers.]]
* BiTheWay: Helen is likely this.
* ButchLesbian: [[spoiler: Ruth Vigers, who successfully passes herself off as Selina's male spirit guide in order to seduce and/or sexually abuse young girls at seances. This also qualifies her as a variant on the PsychoLesbian trope - Waters (obviously) isn't arguing that lesbianism is evil, but this particular lesbian definitely comes across that way.]]
* CanonForeigner: Margaret's fiancé, in the adaptation.
* DarkAndTroubledPast: Most of the characters in the story.
* TheDitz: Pris, Margaret's sister.
* DrivenToSuicide: A year before the novel begins, Margaret attempts a fatal overdose of sleeping medicine after learning that her female lover is planning on marrying her (Margaret's) brother. [[spoiler: Margaret's narrative ends with her about to attempt suicide again after she learns that Selina has betrayed and deceived her. This second attempt is implied to be successful.]]
* EeriePaleSkinnedBrunette: Margaret is one.
* [[spoiler: TheFarmerAndTheViper: Mrs Jelf's kindness is wasted on Selina.]]
* {{Gayngst}}: The primary source of Margaret's depression, following her ex-lover's marriage to Margaret's own brother.
* HairOfGoldHeartOfGold: Selina. [[spoiler: Or so it seems. Eventually subverted.]]
* HeroicBSOD: Margaret has this reaction when [[spoiler: she learns that Selina's been [[UsingYouAllAlong Using Her All Along]].]]
* MyBelovedSmother: Mrs Prior towards Margaret; not so much towards her other children.
* OldMaid: Margaret, who is twenty-nine, is considered this.
* PsychicPowers: Selina works as a psychic medium, and claims to commune with [[OurGhostsAreDifferent spirits]].
* QueerRomance: Between Margaret and Selina and Margaret and Helen. [[spoiler: Also Selina and Ruth, and (depending on your interpretation) Selina and Mrs Jelf]].
* [[spoiler: TheReveal: "Selina's maid, Ruth Vigers".]]
* SpookySeance: Selina works as a spirit medium before being sent to Millbank.
* StalkerWithACrush: Margaret realizes she's become this when she tries to steal Selina's hair and is struck by the sudden understanding of how creepy it actually is.
* [[spoiler: UnwittingPawn: Margaret and Mrs Jelf.]]
* VictorianBritain: set in this era, and very much characteristic of its darker elements.
* VictorianLondon
* YourCheatingHeart: Margaret perceives Helen as this, although [[UnreliableNarrator how fair it is]] is ambiguous.