Act 5 reveals a Juliet that the reader has witnessed in previous parts of the play Romeo and Juliet. Juliet's character changes from an obedient, young, and immature child to a mature, self-righteous, developed young woman.
Although Juliet is not dreaming of marriage at the beginning of the play, in Act I, Scene 3, after Lady Capulet advises Juliet to consider Paris as a possible husband, Juliet obeys her mother's suggestion.
I'll look to like, if looking liking move;
But no more deep will I endart mine eye
Than your consent gives strength to make it fly.
However, after Juliet encounters Romeo at the Capulet masquerade, her character begins to transform. In Act II, Scene 2, Juliet contemplates the idea of being with Romeo, who is a Montague. Juliet fights for what she believes despite all the odds which are against her and her true love. In Act III, Scene 5, after her mother announces that Juliet will marry Paris on Thursday, she quickly dismisses the idea by stating that she will not marry on Thursday.
I pray you tell my lord and father, madam,
I will not marry yet; and when I do, I swear
It shall be Romeo,whom you know I hate,
Rather than Paris. These are news indeed!
She has evolved into a courageous and brave lover. Juliet is persistent in her love for Romeo. Act V is simply an extension of Juliet's maturity. For instance, when Juliet sees Romeo's lifeless body on the floor of the Capulet tomb, she refuses to leave with Friar Laurence. Inevitably, in order to be with Romeo, Juliet kills herself by stabbing herself with a dagger.
It seems you have made an error in your first post about Juliet's transformation in the play Romeo and Juliet. I have already described the change in Juliet's character. However, Juliet's persistence in her love for Romeo is revisited in Act IV, Scene 1. She tells the Friar that she will do anything not to marry Paris. When Friar Laurence describes what the potion will do to her body, Juliet does not hesitate.
Give me, give me! O, tell not me of fear!
In addition, when Juliet returns to the Capulet house, she apologizes for having been disobedient and begs pardon for her disrespectful behavior. She explains to Capulet that she has been to see Friar Laurence in order to cleanse her sins.
Where I have learnt me to repent the sin
Of disobedient opposition
To you and your behests, and am enjoined
By holy Laurence to fall prostrate here
To beg your pardon. Pardon, I beseech you!
Henceforward I am ever ruled by you.
In actuality, Juliet has no intention of marrying Paris. Thus, she is lying to her father about what is happening in her life. Juliet is very different from what the reader witnesses in Act I, Scene III.
I meant to say Act 4. What different side of her personality do you see in her in Act 4?