A woman enters a religious community, usually to take vows. Either as a nun or a religious sister. This is more commonly historically, or in historical works. Reasons of drama have split this up into several types:
Retiring to a conventA woman, often elderly, usually widowed or heartbroken, goes to a convent to take refuge from the world, or perhaps an Arranged Marriage. A rape victim may avoid the malicious gossip and hide in all-female world. After a Heel Face Turn, this may show repentence. Some do not actually take vows, but none of them intend to return to the world. This is usually a Ending Trope, and a Bittersweet Ending at that, because she usually is escaping tragedy to the only refuge she has. It may also be a way to dispose of minor characters without much ado.
ImmuredA woman's father ruthlessly compels her to enter the convent to shut her off from her lover, because he thinks she has disgraced the family, or just to save her dowry. (The permanant form of Locked Away In A Monastery.) Or a woman who promised I Will Wait For You foolishly gave up hope, and her lover returns to find she entered a convent. Horrors! This differs from Retiring to A Convent in that her decision was foolish even if a desperate attempt to escape an Arranged Marriage, and her being bound by her vows is treated as a dreadful thing. Unsurprisingly this particular trope was chiefly Protestant, and was a Discredited Trope by the end of the Victorian era.
VocationUsually found only in explicitly religious literature. A woman wants to become a nun when her family considers it her duty to submit to an Arranged Marriage. She is often -- especially when the story is far removed from Real Life -- So Beautiful Its A Curse, because they think they can get a good match because of it. (A woman who merely wants to become a nun and does seldom appears in stories while she is doing it, because that part of her story lacks drama.) Men can fall under any of these reason as well, although their greater ability to control their own lives and lesser need for a refuge have meant it's a predominately female trope. These tropes can apply to either Buddhist or Christian nuns -- and were used in some Crystal Dragon Jesus pagan situations.
- In the movie Robin And Marian the middle-aged Robin Hood returns from the crusades to discover Marian has, in his absence, taken holy vows and risen through the ranks of the convent to become Mother Superior.
- In LM Montgomery's Emily Of New Moon, the young Emily writes an epic in which her heroine takes vows because she thought the young man she was in love with had died. She asks a priest whether there's any escape. He asks whether there was a feud between the families and is unsurprised to learn there was; he explains that since the heroine had no siblings, she could get a special dispension to leave and marry to resolve the feud. Emily is taken aback by the prospect of putting "special dispention" into verse but gamily tackles it.
- In The Wind In The Willows, Mole recounts how the field mice children had put on a play about a sailor who returned from imprisonment had found his sweetheart had become a nun.
- In GK Chesterton's The Return Of Don Quixote, Michael Herne, familiar with the conventions romantic novel, tracks down his beloved Rosamund, and the first thing he says is to observe that she is a nurse and not a nun. She tells him she had not given up hope of marriage.
- In The Count Of Monte Cristo, Mercedes retires to a convent at the end.
- In Jane Eyre, Charlotte Bronte has one of Jane's cousins convert to Catholicism so that she can then pack her off to a convent, where she became abbess.
- In Madeleine L Engle's A Severed Wasp, an important minor character had entered a convent after her child had died of cancer and she and her husband divorced.
- In Longfellow's Evangeline, the title character became a Sister of Mercy when separated from her betrothed, finally rediscovering him only after he was striken with illness; he dies in her arms.
- This is the main plot of the book and film The Nun's Story, starring Audrey Hepburn. I believe that one may have been based in Real Life originally.
- At the end of The Colossus of Rhodes, Lupus's mother dedicates herself to Apollo and becomes a priestess at a temple for him. It is in keeping with a vow she made years previously for if her son lived.
- In Japanese period works becoming a nun can be the only way for a woman to get a divorce, or indeed avoid a forced marriage: basically, run away, retire into a women's monastery, stay as Buddhist nun for a set number of years (7 if memory serves), and then you're free to go. I remember reading something where the male protagonist helped his unhappily married love interest get away from her husband this way and it was all very bittersweet, knowing they could be together 7 years into the future at the earliest.
- Princess Ilana attempts to do this in book two of the Arcia Chronicles, after being disgraced by her association with the Big Bad Mikhai and losing her flame Rene to Gerika. However, Shander Gardani prevents this by offering to marry her.
- In the Deryni novels, Rothana Nur Hallaj was introduced as a novice nun who had taken her initial temporary vows for vocational reasons before her convent was attacked by Mearan troops. She met Kelson Haldane in the aftermath of that attack, and decided to set aside her vows for him (and another kind of public service as his queen). Things got complicated, and she later takes a place with rediscovered Servants of Saint Camber, partly for the vocation and partly for the shame/heartbreak-induced retirement. Later still, Kelson and Araxie offer her the number two job at the new scola to provide an alternative service job outside a convent.
- In some versions of the Arthurian myths, after the Battle of Camlann Lancelot returns from France to find that Guinevere, repenting for what she has indirectly caused, has taken vows in a nunnery. In the same vein, Lancelot then goes on to become a monk.
- In Ivanoe, Rebecca of course does not become a nun, but she does explicitly compare her dedication to a life of good works and prayer when explaining it.
- * Evvy in the Circle Of Magic book Melting Stones ends the story promising herself that she'll become a novice in the Living Circle religion- not precisely out of a vocation to serve their gods, but because she believes in their philosophy and wants to be a better person.
- In The Saint of Bleecker Street by Gian-Carlo Menotti, visionary Ill Girl Annina says she will take the veil one day. She ultimately does, but dies during the ceremony.
- In Cyrano De Bergerac, Roxanne retires to a convent after being widowed. Cyrano visits her every day.
- In The Sound Of Music, Maria tries to retire to the convent after she realizes she is in love with the Baron.
- In Shakespeare's ''Much Ado About Nothing: When Hero has been accused of being unfaithful, the priest's Plan B is to quietly ship her off to a nunnery where she can live out the rest of her days in anonymity.
- In the Backstory to The Comedy Of Errors Egeon's and his wife Emilia were separated at sea during a storm and both think the other had perished. Emilia entered a convent and eventually beame an abbess (Mother Superior).
- In Hamlet Hamlet tells Ophelia "Get Thee To A Nunnery," which is nowadays taken at face value rather than as a Double Entendre.
- In Pericles Prince Of Tyre, Thaisa becomes a nun in the temple of Diana after she believes her husband and child died at sea. She is wrong, and they are reunited 14 years later thanks to some Divine Intervention.
- In some Kabuki plays, a female character takes temporary vows (by cutting her hair) as a Buddhist nun to duck a forced marriage.
- There's a woman in the Brother Cadfael novel "The Leper of St Giles" who has been a noble's mistress for years, and becomes a nun after his murder.
- One of the prisoners rescued from the slave camp in Dragon Quest V becomes a nun.
- In the H - Game Kango Shicyauzo, this (retiring to a convent) is Sister Maria's backstory. She took her vows after being widowed and is now the head nun at St. Michael's Nursing School.
- St. Clare of Assisi and a friend had to elope in the middle of the night to become a nun. Her family chased after her to try to get her back, but she had already taken her vows -- and cut her long, beautiful hair, which was what really convinced them.
- One medieval saint had hung outside her window holding on with her fingers until her family thought she had fled and then dressed as a man and ran off to get to the convent and escape the Arranged Marriage.
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