social butterfly, and she hosts a weekly missionary circle at Atticus's home and participates in several community functions. Despite presenting herself as an upright Christian woman, she is a staunch racist who claims that Atticus is ruining her family's reputation by defending a Black man. Although Alexandra does not agree with racial equality or her brother's decision to defend Tom Robinson, she genuinely cares about his well-being and wants what is best for Jem and Scout.

In the novel To Kill a Mockingbird, Alexandra Finch Hancock is the aunt of the narrator, the young girl Scout, and the older sister of her father, Atticus Finch. She normally resides with her husband, James, at the Finch ancestral home in Finch's Landing. But at the beginning of chapter 13, she spontaneously arrives for an indefinite stay at the home of Atticus because she feels that the motherless, tomboyish Scout needs to have "some feminine influence."

As a busy, highly organized, and organizing woman, Aunt Alexandra quickly adapts to the social life of Maycomb. As Scout says, "given the slightest chance she would exercise her royal prerogative: she would arrange, advise, caution, and warn." She is preoccupied with heredity and social status and makes every effort to instill in Scout and her older brother Jem, the idea that they are the descendants of a noble clan and should act accordingly.

Throughout the rest of the book, Aunt Alexandra wages a subdued campaign to persuade Scout to abandon her tomboyish ways in favor of more feminine behavior, which the spirited narrator successfully resists. As Scout puts their relationship at the time, "Aunt Alexandra fitted into the world of Maycomb like a hand into a glove, but never into the world of Jem and me."

But as the story unfolds and the stakes for the family are raised, Scout comes to appreciate her aunt's strength and realizes how deeply she cares for Atticus and his two children.

Aunt Alexandra comes to stay with Atticus and the Finch children because of the Tom Robinson trial for the most part.  Atticus will be very busy during the trial and won't have time to take care of the kids even with Calpurnia's help.  Another reason she is there is because she feels she must do what she can to protect the children.  She knows that the trial may get ugly and she disagrees with Atticus's involvement anyway, so she thinks that she can shield the children from any ugliness that may occur.  She feels that she must be there, too, to protect the family name.  Aunt Alexandra believes that Atticus is raising the children incorrectly.  She sees him as being much too liberal with the children and she wants to counteract that.  She is a staunch conservative in all her views.  She feels that one's family background is more important than what one does and that is not how Atticus has raised Scout and Jem.  Ultimately, she loses this battle of child-rearing philosophies.  Her reasons for being there are varied and each reason reflects what kind of person she is.

When Aunt Alexandra first arrives at the Finch house, Scout thinks she is there for a short visit. She quickly finds out that her aunt's stay will be much longer than that. Aunt Alexandra explains why she decided to come stay:

"Jem's growing up now and you are too," she said to me. "We decided that it would be best for you to have some feminine influence. It won't be many years, Jean Louise, before you become interested in clothes and boys—" (To Kill a Mockingbird, Chapter 13)

Scout listens to her aunt's words and wants to protest. She knows that she is not interested in boys or in clothes. She knows that Calpurnia is always around to be a feminine influence on her. Despite Scout's inner protests, she does not say anything to Aunt Alexandra.

Aunt Alexandra comes to be a mother figure in the Finch household. She plans to keep an eye on the children during the trial. She is a serious woman who believes in proper behavior at all times. Specifically, she thinks that Scout should behave more like a young lady. Aunt Alexandra cares about mingling and being sociable with the area ladies.

Aunt Alexandra decides to stay with the Finches to give Scout "some feminine influence" (Chap 13). However, it has become apparent that there is more to the reason than that as Atticus lets Scout know that he will be very busy during the summer, he has the trial, and Aunt Alexandra is really "doing me [Atticus] a favor as well as you all" (Chap. 13). Aunt Alexandra's discipline becomes a difficult barrier for Scout and places a wedge between Scout and her father, Atticus, for a short while.

While Aunt Alexandra does visit her brother and his children on occasion, her arrival in Chapter 13 seems precipitated at least, as much by her sense of family solidarity and sense of class as her preoccupation with the importance of "propriety" which demands Scout's need for "feminine influence." For, Alexandra arrives in the chapter that follows after the one in which the black maid Calpurnia takes the children to church and the one previous to that in which Mrs. Dubose hurls insults about Atticus at Jem and Scout, accusing him of being a "n*****-lover" because he violates social mores and takes on the defense of Tom Robinson. 

That Aunt Alexandra holds to these social mores is evinced in her immediate holding of the Missionary teas. In a later chapter, the details of these teas are described with those like Mrs. Merriweather, who voices the conventional wisdom of her class as she disparages her maid for grumbling about her pay. She also remarks that "some good, but misguided people" are causing the blacks such as her maid to become "sulky."

More immediate evidence of Aunt Alexandra's attitudes comes in the following chapter, Chapter 14, when, having been disturbed by the gossip of the town upon learning that the children attended her church, as well as the "improper" position of Calpurnia in the Finch family, she advises her brother to dismiss his maid, "We don't need her any more." Atticus's reply,

"You may think otherwise, but I couldn't have got along without her all these years. She's a faithful member of this family and you'll simply have to accept things the way they are."

certainly does not please Aunt Alexandra.

Aunt Alexandra comes to stay with Atticus, Jem and Scout because, as she explains to Scout in Chapter 13 of To Kill a Mockingbird:

“Jem’s growing up now and you are too,” she said to me. “We decided that it would be best for you to have some feminine influence. It won’t be many years, Jean Louise, before you become interested in clothes and boys—”

Throughout Harper Lee’s novel of growing up in the American South during the 1930s, the story’s narrator, Scout, makes sure that the reader understands that Atticus’s sister Alexandra is the bane of her existence.  Scout is what used to be called a “tomboy,” a girl who dressed and behaved more like a boy than the image many people had of a proper young girl.  This situation exists in direct contravention of Aunt Alexandra’s perceptions of “girlhood.”  In a passage in Chapter 9, Scout summarizes her aunt’s views of the young girl’s demeanor:

“Aunt Alexandra was fanatical on the subject of my attire. I could not possibly hope to be a lady if I wore breeches; when I said I could do nothing in a dress, she said I wasn’t supposed to be doing things that required pants. Aunt Alexandra’s vision of my deportment involved playing with small stoves, tea sets, and wearing the Add-A-Pearl necklace she gave me when I was born; furthermore, I should be a ray of sunshine in my father’s lonely life. I suggested that one could be a ray of sunshine in pants just as well, but Aunty said that one had to behave like a sunbeam, that I was born good but had grown progressively worse every year.”

Aunt Alexandra, who had remained at the family’s ancestral estate, Finch’s Landing, is an occasional visitor to Atticus’ home, particularly at Christmas, and regularly expresses her concern that her brother is failing at raising Scout as a proper young lady.  When the decision is made for Alexandra to move in with Atticus, Jem and Scout, she arrives with her luggage and promptly greets Scout in a manner certain to grate on the young girl:

“Put my bag in the front bedroom, Calpurnia,” was the first thing Aunt Alexandra said.

“Jean Louise, stop scratching your head,” was the second thing she said.

Scout is a product of her environment.  She does enjoy doing activities traditionally associated with masculinity.  That is the world in which she lives.  The town of Maycomb is small, rural and poor.  Scout’s only sibling is an older brother, and her best friend, when he comes to Maycomb for the summer, is Dill. In effect, she spends the bulk of her time with male figures, with which she seems perfectly fine.  Aunt Alexandra’s intrusions into her life are unwelcome.  Alexandra comes to live with them, however, with the intent of transforming Scout into somebody she isn’t.  That she greets Scout not with the girl's preferred nickname but with her formal feminine name does not bode well for Scout.

At the end of chapter 12, Jem and Scout return home to find Aunt Alexandra waiting for them on their front porch. At the start of chapter 13, Aunt Alexandra explains to Scout that because both she and Jem are growing up, she and Atticus believe that Aunt Alexandra's feminine influence will be helpful to Scout. Scout does not agree with this assessment of need, and when Atticus comes home and explains the decision, Scout gets the feeling that Aunt Alexandra had made the decision to come live with them all on her own.

Aunt Alexandra's desire to come and live with Atticus and the children may stem from a desire to be helpful during a difficult time and a genuine sense of familial duty to her brother, or it may come from a less generous impulse that serves Aunt Alexandra's needs more than anyone else's. Scout tells the reader that Aunt Alexandra ignores her question about missing Uncle Jimmy, so perhaps Aunt Alexandra is bored by her life at home and wants to get involved in something more interesting than her silent husband. Her arrival tells the reader and the residents of Maycomb that she is certainly interested in contributing to the upbringing of Jem and Scout, but her motivations to do so are less clear.

In chapter 13, Scout and Jem return home from their visit to First Purchase African M.E. Church and are surprised to find Aunt Alexandra waiting on their front porch. After Calpurnia takes Aunt Alexandra's bags inside, Scout asks her aunt if she has come for a brief visit. Alexandra proceeds to explain that she and Atticus decided that it would be a good idea for her to spend some time with the family in order to provide some "feminine influence" for Scout, who is rapidly maturing and will be interested in boys and clothing soon. Since Atticus's wife passed away, Calpurnia and Miss Maudie are the main female role models in Scout's life. However, Aunt Alexandra feels that she will also be a better influence on Scout, who enjoys wearing overalls and behaving like a tomboy. Aunt Alexandra's willingness to stay with her brother's family demonstrates her compassion and loyalty. Aunt Alexandra wants what is best for Atticus and his children, which is why she is willing to leave her home and stay with her brother's family to positively influence Scout.

This question is not fully explained in To Kill a Mockingbird, but it appears that Alexandra felt that her feminine touch was deserately needed in the Finch household. It is clear to Scout, however, that Atticus has not requested her presence:

I had an idea... that Aunt Alexandra's appearance on the scene was not so much Atticus's doing as hers. Aunty had a way of declaring What Is Best For The Family, and I suppose her coming to live with us was in that category.

Atticus probably found it impossible to discourage Alexandra from moving in, and he must have thought that she would be useful for a few weeks, since he was going to be busier than usual dealing with the Tom Robinson trial. But Alexandra was dismayed at Scout's unladylike ways, and she thought her brother was doing a poor job of raising them. Alexandra thought she would best serve as the mothering symbol in the household, although Atticus was perfectly happy with Calpurnia serving in the same mold. It is clear that Alexandra was far from the perfect mother: Her own son had left home as soon as possible; her grandson, Francis, was a spoiled brat; and she and her husband, Jimmy, barely spoke to one another. But Alexandra believed Jem and Scout needed another Finch female in the home--she considered Calpurnia only an employee and not a member of the family, like Atticus. She believed the children needed lessons in "gentle breeding" and the Finch family heritage, so she left Finch Landing for an extended stay--and never left.

Aunt Alexandra shows up at the end of Chapter 12 of To Kill a Mockingbird. Supposedly, she is there to give some feminine guidance, be a mother figure, for Scout. It is clear to the reader, however, that Calpurnia has been filling that role quite well prior to Alexandra's arrival. Alexandra claims that both she and Atticus decided it was time for Scout to have a feminine influence. But Atticus indicates that it was more Alexandra's idea than his. 

Near the end of Chapter 13, Atticus reveals why Alexandra really has come to stay with the Finches. 

“She asked me to tell you you must try to behave like the little lady and gentleman that you are. She wants to talk to you about the family and what it’s meant to Maycomb County through the years, so you’ll have some idea of who you are, so you might be moved to behave accordingly” he concluded at a gallop.

Atticus spoke these words to the children "at a gallop" because he wanted to get them out. Perhaps Alexandra was listening. Atticus did not believe in any of this. He wanted his children to behave and become upstanding citizens. But he didn't want them to think they are better than others simply because of family or social traditions. At the end of the chapter, Atticus tells the children to forget what he just said. 

Alexandra feels inclined to impress upon the children their family heritage. Atticus agrees to this, perhaps thinking he could use some parental help during the trial. Or, perhaps Atticus recognizes that Alexandra needs something to do. In Chapter 9, Scout notes that Alexandra's son, Henry, left home "as soon as was humanly possible." Although Atticus disagrees with Alexandra's views on social traditions and "knowing your role," he recognizes that most people in Maycomb think the way she does. Atticus will continue to reject this insistence on social traditions but he is willing to have Alexandra (who does have good intentions) stay with them to give her a sense that she has some purpose. 

The editor above gives you a very accurate answer to your question.

To add, Aunt Alexandra has done something that few are ever able to: she moved Atticus to act in a way outside of his comfort zone. She manipulated her way onto the scene within the presence of a pretty powerful character. Maybe part of the purpose the author has Aunt Alexandra there is to be what we call a 'foil' in literature. A foil is an exact opposite to another character. Even though she is Atticus' sister, Aunt Alexandra is indeed an exact opposite of Atticus in many ways.

She wants the kids to think in terms of social appropriateness. Atticus wants them to think in terms of moral righteousness.

Hope that helps contribute to the ideas that the previous editor gave.

When Scout and Jem arrive home from Calpurnia's church at the end of Ch. 12, they find Aunt Alexandra sitting in a rocking chair on the porch. They ask her if she's come for a visit, but her reply is much more discouraging (at least for Scout).

"Well, your father and I decided it was time I came to stay with you for a while."

"For a while" in Maycomb meant anything from three days to thirty years. Jem and I exchanged glances.

"Jem's growing up now and you are too," she said to me. "We decided that it would be best for you to have some feminine influence. It won't be many years, Jean Louise, before you become interested in clothes and boys--"

I could have made several answers to this: Cal's a girl, it would be many years before I would be interested in boys, I would never be interested in clothes . . . but I kept quiet.

So, it seems that Atticus and Aunt Alexandra have decided that Scout needs "feminine influence". That is, she's going to teach Scout how to be a girl, in Aunt Alexandra's definition of the term. Of course, it's more likely that Aunt Alexandra decided Scout needed a woman's guidance, & Atticus couldn't say no. Of course, it's also telling that Alexandra doesn't consider Calpurnia a suitable female role model for Scout, most likely because she's black and in the position of a servant in the Finch household. Although all the Finches (Atticus included) consider Calpurnia as a second mother to Jem and Scout, Aunt Alexandra simply cannot accept this. She may also simply not trust the role to anyone but herself.

Scout does not have a particularly close relationship with her aunt. In chapter 9, Scout explains:

Aunt Alexandra would have been analogous to Mount Everest: throughout my early life, she was cold and there.

Because of this, Scout is not particularly excited when her aunt comes to live with them at the end of chapter 12. At the opening of chapter 13, Jem offers to help Aunt Alexandra with her bags. Scout describes these events:

Calpurnia picked up Aunty’s heavy suitcase and opened the door. "I’ll take it," said Jem, and took it. I heard the suitcase hit the bedroom floor with a thump. The sound had a dull permanence about it.

Before Scout hears any reasons for her aunt's visit, Scout already sees hints that she might stay in Maycomb for a long time. (This is seen by the amount of heavy luggage that she is traveling with.) Scout asks her,

“Have you come for a visit, Aunty?”

Aunt Alexandra responds,

"Didn't your father tell you? . . . Well, your father and I decided it was time I came to stay with you for a while."

Immediately, Scout and Jem are concerned by her statement. They realize that "a while" is a very vague term, and they are not excited about having their aunt living with them for long.

Aunt Alexandra then explains the reasons that she and Atticus decided that it would be wise for Aunt Alexandra to move in for a while:

"Jem’s growing up now and you are too. . . . We decided that it would be best for you to have some feminine influence. It won’t be many years, Jean Louise, before you become interested in clothes and boys—”

Aunt Alexandra claims that she is coming to live with them to help Scout have an example of what womanhood should look like. Scout, however, thinks to herself that Calpurnia (their nanny / maid) is a woman. She wonders silently why Calpurnia cannot help her to understand what womanhood looks like.

When Atticus gets home, he explains to Scout that Aunt Alexandra is in town for much more than merely teaching her how to be a proper lady. He says to her,

"We felt it was time you children needed—well, it’s like this, Scout, . . . Your aunt’s doing me a favor as well as you all. I can’t stay here all day with you, and the summer’s going to be a hot one.”

Atticus explains that Aunt Alexandra is coming to help keep the kids safe and comfortable. Since Atticus is helping with an extremely controversial court case, he will be away from the house a lot. Many people are upset about the court case and could make life uncomfortable for Atticus's children (Scout and Jem). He wants to make sure there are extra people around to look out for the well-being of his children while he is busy. When he says it is going to be a hot summer, he doesn't mean simply heat from the sun. He is metaphorically referencing the tension and unrest in Maycomb over Tom Robinson's court case.

Atticus' sister, Alexandra, comes to Maycomb in order to take care of Jem and Scout during the Tom Robinson trial, but it appears that she plans to stay much longer than that. Atticus had not told the children about her arrival, so it was a surprise to them. Alexandra explained that

"We decided that it would be best for you to have some feminine influence."

Scout knew that "There was a story behind all this," and she waited to hear Atticus' explanation. His answer was not much clearer, for Scout was left "not understanding a word he said."

Atticus had apparently gotten tired of his sister's nagging about how unladylike Scout had become, and he finally gave in to her request to "stay for a while." Since Alexandra did not get along with her husband, Jimmy, it could be that she was also lonely in her isolated Finch's Landing home and yearned for the social life that Maycomb offered.

Atticus's sister, Alexandra Hancock, makes her surprise "visit" to the Finches just prior to the beginning of the Tom Robinson trial. After she arrived,

I heard the suitcase hit the bedroom floor with a thump. The sound had a dull permanence about it.

Her appearance was news to Jem and Scout, and Aunt Alexandra told Scout that

"... your father and I decided it was time I came to stay with you for a while."     "For a while" in Maycomb meant anything from three days to thirty years.

Indeed, Alexandra never departs the Finch household, leaving her husband, Jimmy, behind at Finch's Landing. The decision to come appears to be Alexandra's alone, despite assurances from Atticus that his sister was doing him a favor. He would be much busier attending to the trial, so it can be assumed that this was the reasoning behind his sister's visit. Alexandra believes the children needs a feminine touch in the house, and that Scout in particular needs training in how to become a lady. Alexandra obviously tries to bully her brother into her way of thinking, but Atticus stands firm when Alexandra tries to have Calpurnia fired.

Aunt Alexandra is Atticus's sister, but Scout does not have a warm feeling about her.  She says,

"Aunt Alexandra would have been analogous to Mount Everest; throughout my early life, she was cold and there." (pg 76- chapter 9)

Aunt Alexandra has always had a problem with Scout and her overalls. She could not see how Scout hoped to become a lady if she wore pants.  She thought little girls should be playing with dolls and tea sets.  Scout is hurt because her aunt thinks,

"....one had to behave like a sunbeam, that I was born good but had grown progressively worse every year." (pg 81 - chapter 9)

Atticus was fine with the way Scout was and told her to just be herself.  However, Aunt Alexandra and Atticus have a discussion, and it was decided that Aunt Alexandra would come to stay with them for a while. She tells the children,

"We decided it would be best for you to have some feminine influence.  It won't be many years, Jean Louise, before you become interested in clothes and boys ___" (pg 127 - chapter 13)

Atticus needs her help, but she is also there to help with the children during this terrible time of the trial.  The children are going to need her support while he is trying this case.  Atticus tries to explain to the children,

"She asked me to tell you that you must try to behave like the little lady and gentleman that you are.  She wants to talk to you about the family and what it's meant to Maycomb County through the years, so you'll have some idea of who you are, so you might be moved to behave accordingly." (pg 133 -chapter 13)

As Scout gets to know her aunt, she realizes what her role will  be in the future.  When she attends a tea party/business meeting hosted by Aunt Alexandra, she wears a pink dress and helps to serve refreshments.  She comments,

"There was no doubt about it.  I must soon enter this world where on its surface fragrant ladies rocked slowly, fanned gently, and drank cool water.  But I was more at home in my father's world." (pg 233 - chapter 24)

Aunt Alexandra says that she moves into provide Scout with a women's influence, but the timing of her move indicates that there may be other factors involved.  She moves in just before the start of the Tom Robinson trial, and although she disapproves of her brother defending Robinson, as family this may be her way of showing her brother support.  She knows that Atticus will be very preoccupied with the trial and will have little time for his children and this is one way she can help him without being involved with the trial  Secondly, her quick and complete involvement in town life suggest that part of the reason for the move is her own need of the social outlets that life in town has to offer compared to the isolation at Finch's Landing.   It surely seems that her coming to town has more implications than her desire to civilize Scout.

Aunt Alexandra moves in with Scout, Jem, and Atticus "for a while" in order to give Scout some "feminine influence." Scout narrates, however, that Aunt Alexandra's presence is "not so much Atticus' doing as hers."

We never know for sure exactly what transpired between Atticus and Alexandra that eventually led to her coming to live in Maycomb. It is clear that Alexandra believes that both of the children need some female guidance and that Scout particularly needs to begin acting more like a little lady. It is also no coincidence that Alexandra appears shortly before Atticus returns from Montgomery and begins preparations for the Tom Robinson trial. It's a surprise to Scout, however, who believes that Aunty has just come for a visit. According to Alexandra,

"... your father and I decided it was time I came and stayed with you for a while."      "For a while" in Maycomb meant anything from three days to thirty years.  (Chapter 13)

When Atticus personally broke the news to his children, he explained that

"We felt it was time you children needed--well, it's like this, Scout... Your aunt's doing me a favor as well as you all. I can't stay here all day with you, and the summer's going to be a hot one."  (Chapter 13)

When Atticus asked her if how she felt about it, Scout lied and said "I would like it very much." Scout didn't understand Atticus's explanation but

... I had an idea, however, that Aunt Alexandra's appearance on the scene was not so much Atticus's doing as hers.  (Chapter 13)

Although Atticus may have reluctantly agreed to let his sister come to live with him, he did manage to establish that he was the head of the household, firmly rejecting her idea that they fire Calpurnia. As for Alexandra, her stay in Maycomb apparently proved to be a fairly long one.

Atticus Finch’s sister, Alexandra, comes to stay at his home on his request, but Scout resists believing that her father could be the reason behind her arrival. Already busy with his law practice and serving in the state assembly, Atticus knows that his involvement in the Robinson case will require even more time away from the house than usual. While he also knows that his sister is more conservative than he is, Atticus understands that his children need an adult in the house at all times. After his wife passed away, he relied on Calpurnia to keep the home running, but he understands that her hours are limited.

Alexandra is happy to help her brother and genuinely glad to spend time with his children, but she is very set in her ways and committed to the idea of the social superiority of the Finch family’s “gentle breeding.” She is also very unused to being subjected to constant questioning of the sort Scout routinely dispenses. Her presence causes some friction in the house as she, Atticus, the children, and Calpurnia all have to get used to co-existing. Scout, as the youngest and as a female, is more often on the receiving end of her aunt’s efforts at control, and she is more resistant to them. Her aunt tells her,

We [Atticus and I] decided that it would be best for you to have some feminine influence. It won't be many years, Jean Louise, before you become interested in clothes and boys . . .

Scout, who resists using her real name, is already “engaged” to Dill, but she plays with him and Jem largely as one of the boys. Clothes are even further from her mind. Toward the novel’s end, however, Scout adopts a feminine outfit to placate her aunt during her missionary society meeting—but still wears her pants underneath her dress. When the news comes that Tom Robinson has been killed, Alexandra breaks down, and Scout overhears a genuine conversation between her and Miss Maudie. As she realizes that her role will be different from that of her brother, Scout decides that she can, at least temporarily, be as much of a lady as the other women.

One day, Scout and Jem come home to find Aunt Alexandra sitting on their front porch.  This is unusual, because she rarely visits.  She says she is planning to stay for a while, and Scout feels uneasy.  She does not know how long a while will be.  Aunt Alexandra tells Scout that she came "to have some feminine influence" on her (To Kill a Mockingbird, Chapter 14).  She wants to prepare Scout as she becomes a young lady.

Atticus asks Scout if she would like for her aunt to live with them.  Scout lies and answers that she would.  She truthfully does not enjoy spending time with her aunt.  Aunt Alexandra is often negative toward Scout, and she shows her disapproval.  On top of that, her aunt is strict and meddling.  Aunt Alexandra wants Scout to behave like a lady.  Scout would rather play outside with Jem and Dill and wear denim overalls all day.