A trio of girls/women: the innocent child, the steady, wise wife, and the sexual, often sexually predatory seductress.
The wife, the wiser, calmer aspect, is someone around whom one could build a home life. The seductress is sexually experienced and independent. The third, the "child" (who does not have to be a child literally) will be an innocent, perhaps painfully so.
So in short, a triad of:
All three character types are considered to be very feminine — with Child representing Light Feminine, Seductress representing Dark Feminine and Wife being in the middle, just like the movie that the trope gets its title from. Instead of Beauty, Brains and Brawn it's (pretty) Beauty, (pleasant) Beauty, and (provocative) Beauty. Instead of butch, femme, and neither it's (girly) femme, (lady-like) femme, and (womanly) femme.
When adding examples, please note that the sexual aspect of the "seductress" must be present, and cannot be replaced with some other characteristic, like "anger" or "strength" or "selfishness". Also note that the second character is wife, not just a maternal character, a woman who gives birth, or one with any other motherly trait, but one who would make a good life partner. The innocent aspect of the child must be present, not Kids Are Cruel. Please don't put a square peg in a round trope.
Compare The Three Faces of Adam, the not-quite Spear Counterpart.
Contrast Madonna-Whore Complex where any individual woman must be either "sexual and attractive" or "virtuous and maternal", but cannot be both; and The Hecate Sisters, where the "maiden" combines the naivete of the child with the sexuality of the seductress, the "mother" combines the liveliness of the child with the maturity of the wife, and the "crone" doesn't have close counterpart.
Lime is youthful in appearance, overly cheerful, and a bit dumb at times, making her the child.
Cherry is extremely domestic and focused on being proper which causes her to appear more even-tempered and less impulsive than Lime or Bloodberry. Often when the other two are running rough-shod over the show's protagonist she is the one to stop and consider his feelings. She fits the wife archtype in addition to really wanting to be the protagonist's wife.
Bloodberry is more shameless than Cherry, and more sexual in her intention. Additionally, the is the only one of the trio with a mature-looking body.
Of the three girls who are in love with Kurusu in Daily Life with Monster Girl, Papi is the Child because she is joyous, absent-minded, and a bit naive; Centaurea is the Wife because she is incredibly honorable and chivalrous, as well as unerringly loyal to Kurusu; and Miia is the Seductress because she is very flirtatious, trying to seduce Kurusu on multiple occasions.
In Change 123, Motoko's three alternate personalities follow this mold. Mikiri is the innocent child, Hibiki is the Hot-Blooded seductress and Fujiko is the wise, motherly wife.
Madlax gives us Margaret Burton as the Wife (gentle, quiet Ordinary Highschool Student), Madlax as the Seductress (deadly and sexy hitwoman with a heart), and Laetitia as the Child (creepy-lookingLonely Doll Girl). It's even more meaningful when we find out that Laetitia and Madlax are actually parts of Margaret's whole self, released when she killed her Brainwashed and Crazy father (and the first Madlax) in self-defense years ago. In the end, Margaret decides to accept her past and split herself again in three, adopting Laetitia as her little sister and releasing Madlax so she can live her life as she sees fit.
In some versions of the Legion of Super-Heroes, Triplicate Girl (or Triad) has a different personality for each body; Triad-Purple is brash and outgoing (seductress), Triad-Orange is shy and quiet (Child) and Triad-Neutral is the stable figure who has to keep the other two together (Wife).
In the DC Universe series Gotham City Sirens, Harley Quinn plays up her clownish persona by acting ditzy and naive (child), Catwoman is pragmatic and sensible (Wife), and Poison Ivy is a vamp known for using her sex appeal to get her way (seductress). They team up.
Heroic Trio has a young ditz, a motherly type, and a (formerly) dark seductress as the main characters.
Deconstructed in Black Swan. At first glance, the older and Prima Ballerina Beth who is Thomas's girlfriend would seem to be the wife, the sweet, innocent Nina is the child, and the sexy and wild Lily would be the seductress. But it turns out that Beth is clingy and insane, Nina is very repressed and begins to mature throughout the film, and while Lily does enjoy casual sex she is not as manipulative or self-serving as Nina believed.
Twilight has Bella's Na´ve Everygirl contrasted with Esme (wife), who warmly welcomes Bella into her home and later restores a cottage on the Cullen estate for Bella and Edward, Rosalie (seductress), who is jealous of Edward's affection for Bella because she the one who has always been desired by men, and Alice (child), who values Bella's safety above all and cares for her like a sister.
Helen and her two friends Millicent and Annabella who all marry into the same group of friends form this trio in The Tenant of Wildfell Hall. Helen is the wife, steadfastly devoted to her marriage even when it begins to fall apart; she takes her marital duties so seriously that she returns to Grassdale when Huntingdon is ill to care for him. Millicent is the child, innocent, idealistic, and very passive, needing others to take care of her. Annabella is the seductress, tricking Lord Lowborough into marriage with her beauty and luring Huntingdon away from Helen, the death blow for Helen's love for her husband.
David Copperfield gives us the three ladies whom David loved through his life. His First Love is Little Emily, the Seductress (aware of her good looks, may or may have not been a prostitute and her best friend Martha is one, ends up running away with Handsome Devil Steerforth and is massively broken for that); his Second Love Dora is The Child (spoiled, sweet, naive, even nicknamed 'his child wife' and what drew David to her may have been his Mommy Issues since she was similar to his also very child-like mother Clara; and finally, his third love and second wife Agnes is the Wife (reliable, the "angel of the house", softspoken, a Proper Lady)
In Knots Landing, the three main women fill these roles perfectly: Karen is The Wife, the wiser, calmer aspect. Abby is The Seductress — sexually experienced and independent. Val is The "Child" (although she's the same age as the other women) and is innocent, perhaps to the point of na´vetÚ.
Although all the same age the girls on Friends can be viewed this way, with flirty and sophisticated Rachel as the seductress, innocent and quirky Phoebe as the child and capable, responsible Monica as the wife.
The three women in the study group of Community fit this to a tee:
Shirley is the Wife; she is not only the oldest, she tries to be the voice of reason and mediator wherever possible, as well as the group's moral center.
Britta is the seductress; she has the most varied sex-life and uses sex to get what she wants now and again, she is the most traditionally attractive, and she is the most cynical.
Annie is the child; she is the youngest and the most idealistic and naive, something she often gets made fun of for.
The three female leads of Mad Men: Joan is the seductress, completely capable of using her sexuality to get what she wants. At first glance, Betty (Stepford Smiler housewife) would be the Wife and Peggy (Plucky Office Girl) would be the child, but before long, childishness establishes itself as one of Betty's crucial qualities if not her Fatal Flaw, and Peggy displays a determination to leave behind the role of wide-eyed little girl and becomes a capable woman and Don's equal in a way Betty (his actual wife) never was.
Joan also serves as a maternal role, taking care of business for the younger secretaries and being an excellent confidant for Don, Peggy, and Lane. Even becoming a Mother who would make rather risky decisions for her son's well-being.
The three ladies of The Golden Girls minus Sophia. Rose was the child (sweet and naive), Dorothy was the wife (calm and sensible) and Blanche was the seductress (sexy and fiery.)
With Prue's death at the end of Series Three of Charmed, Piper becomes the wife, eventually growing from insecure middle sister to capable eldest sister. She is also the first one to actually get married and have children. Paige is the child, being the youngest, newest member of the family and the least experienced in the ways of magic. Phoebe is the seductress, having the most active love life of the sisters.
Certainly alluded to in episode three of the BBC/Starz series The White Queen, in the scene in which Jacquetta Woodville, her daughter Queen Elizabeth (consort of Edward IV, not the more famous daughter of Henry VIII), and her daughter, also named Elizabeth, use witchcraft to send a terrible storm against Richard Neville, Earl of Warwick, and George Plantagenet, Duke of Clarence. Jacquetta, the grandmother and the most knowledgeable in witchcraft, and with the steadiest, most phlegmatic temperament, is the crone or mother figure, or the wife, although by that time she is a widow (which is why they are trying to kill Warwick and Clarence in the first place). Queen Elizabeth, the beautiful (and that is historically accurate, as the accounts all agree that she was gorgeous) young wife of the king, with the most passionate temperament of the three, is the seductress. Little Elizabeth, being at that time only three years old, and not really understanding just what they are doing or that she is helping with the spell, is the innocent child.
Margo is the sly , hot headed, scheming seductress.
Bubbly and bubble-brained Lu Ann is the child.
Stable, domestic Tommie as a very dull Wife (ironic seeing as how she's eternally single.)
Fate/stay night has Ilya as the Child (acts very precocious and is literally stuck in a child's body), Arturia as the Wife (partner to The Hero and eventually enters into a relationship with him), while both Rin and Sakura have different aspects of the Seductress (Rin is virginal yet very headstrong and independent, while Sakura is sexually experienced even if NOT by choice but emotionally dependent).
An alternative interpretation focusing on the heroines: Saber is the Child, unused to personal relationships and clinging to a childish ideal. Rin is the Seductress, competent and fiery but also insecure. Sakura is the Wife, sexually experienced and dedicated to the happiness of Shirou above her own.
It's not really canon, but if we count Past Sins, then the three ponies touched by the Nightmare Forces fit this trope: we have wise Luna (wife), innocent Nyx (child), and flirty Rarity (seductress).
Final Fantasy games in general have a pattern to their three playable females (and there are always three; see the Three Females Rule in the Grand List) are almost always represented as an Innocent Princess type, a Tough but Sexy Type, and a Perky Girl type. Occasionally this overlaps with the faces of Eve archetypes, although often times the Tough but Sexy character is not a seductress but more passively sexy.
Final Fantasy VII has an interesting version of this. For starters, one of the three women is an Optional Party Member, and secondly, the two who weren't looked like they played one role, but in fact were the opposite:
Tifa (looks and acts the part of the seductress) is in fact most reasonable and sensitive — also the secret-keeper of the group (her last name, Lockheart foreshadows this).
Aerith (looks the part of the wife) is in fact boisterous, flirty and street-wise because of her upbringing in the slums.
Yuffie (the optional one) both looks and acts like the child.
Lightning (believe it or not) plays the part of the wife. She's the most motherly and caring of the group — particularly towards Hope and (much later) Snow. She is also said to have acted this way around Serah.
Fang plays the role of the seductress; she is the most flirty and provocative of the group, and is quite Hot-Blooded at times. Interestingly, these aspects of her personality originally belonged to Lightning (with Serah as the seventh party member and playing the part of the wife), but when Fang was made a woman, they were given to her instead.
Child - Leliana is on the ingenuous side of Ping Pong Na´vetÚ. She had been drawn into espionage and political intrigue by the sense of glamor, excitement, adventure, and it wasn't until after she was burned by the shady side that she realized she had relied on Marjolaine to shelter her from that so she could continue to innocently play games. Instead of becoming the jaded manipulative spy, she chose to preserve her purity of spirit by seeking sanctuary with a stable and nurturing parental surrogate, the Church of Andraste.
Seductress - Morrigan is cynical, instatly contemptive of others, knows her sex appeal and how to use it to her advantage. Before the end, she will try to seduce a Warden to get what she wants, whether or not that Warden has ever shown interest in intimacy with her, or even likes her at all.
Wife - Wynne is cool-headed, perceptive, compassionate, and far more worldly wise than the confined life of a Tower Mage would suggest. She's no stranger to giving and receiving pleasure in her relationships. Modest and pragmatic, but not overly prim, she simply flirts with more decorum.
Wife - Aveline is the only character to start the story married (although she is quickly widowed), and the only character almost guaranteed to end in a relationship. She's wise, honest, caring, no-nonsense, and a capable leader; she takes her responsibilities as captain of the city guard seriously and strives very hard to keep the men and women under her as safe as possible.
Seductress - Isabela flirts with everyone and makes no bones about her love of sex and no attempt to hide her past sexual exploits. She is the most provocatively dressed member of the party, and offers to teach Merrill how to do body-shots.
In Super Robot Wars Original Generation, resident Ms. Fanservice Excellen Browning makes up a group called the "Three Beautiful Sisters", consisting of herself, Viletta Vadim and Lamia Loveless. Lamia is the Child (due to her recent discovery of what it's like to be a human, made more obvious in Original Generations when she gains a Split Personality that sounds like a little girl), Viletta is the Wife (she's the sensible and capable commander of the SRX Team), and Excellen as the Seductress (bloody obvious).
Among Excellen's clones, this trope also applies: Alfimi as the innocent yet Creepy Child, Lemon as the sensible right hand of Vindel Mauser, and Excellen still as the Seductress.
The Highschool Girls team from KOF 2003 had Athena Asamiya as the Wife (more experienced membress, leader of the group, Idol Singer who sings to keep the spirits of her fans high no matter what), Hinako Shinjou as the Child (naive, Spoiled Sweet, a Cute Bruiser who wants to show how girls can do what they wish) and Malin as the Sedductress (Combat Pragmatist, outspoken, veeeeery short Magic Skirt)
Alternatively, in KOF 96 and KOF 97 there are some changes to the Women's Team's roster and they fit in here as well. KOF 96 has KasumiTodoh replacing Yuri as the Child, and in KOF 97 ChizuruKagura becomes a secondary Wife.
In The Legend of Zelda Oracle games, the three Oracles (shown in the page image) are Din, an outgoing dancer (seductress); Nayru, a gentle singer (wife); and Farore, a helpful intellectual (child). Unfortunately, the game which was supposed to feature Farore was cancelled. Incidentally, the Oracles share their names with a trio of goddesses in the series mythology (the goddesses of power, wisdom, and courage), but we don't know enough about them to know if they match the trope.
In Fire Emblem there are several all-female Power Trios, but the one that fits in the best is the Pegasus Knight sisters from Fire Emblem 7. The Wife is the eldest sister Fiora (who even tends to be overprotective and strict), middle sister Farina is The Seductress (strongwilled, materialistic, yet with a hidden gentle side) and the Child is little sister Florina (Shrinking Violet)
All of the girls that can potentially be fathered by Chrom count as this in Fire Emblem Awakening: Patient and serious Lucina is the wife, strong-willed and rough Kjelle the seductress and clumsy, innocent Cynthia the child. Heck, even Chrom's wife choices themselves can be this: Robin and Sumia (wife), Sully and Maribelle (seductress), and Olivia (child).
In the mistresses of Overlord II: Kelda would serve as the child (least evil of the Mistresses and the only one to actually love The Witch-Boy), Juno the seductress (Gold Digger) and Queen Fay is the Wife figure (the one most "Equal" to the Witch-Boy).
The NOL girls of BlazBlue. Noel is shy, innocent and idealistic (the Child), Tsubaki is level-headed and academic (the Wife), and Makoto is the most blatantly fanservicey (the Seductress).
The past arc in the Magic Guild girls too: Caelica the bright younger sister girl, Trinity the sensible, if bookish one, and Nine the fiery and buxom one.