What are three characteristics of the Nurse in Romeo and Juliet?

While playing a loving and comic role, the Nurse of Romeo and Juliet later becomes a rather fickle character.

The Nurse embodies romantic comedy as the inarticulate messenger and "sparring partner" with Mercutio. Her prolix ramblings lighten the more serious moments as, for instance, when she and Lady Capulet talk in Act I, Scene 3. When Lady Capulet mentions that Juliet is not fourteen, the Nurse rambles on and on about this and other numbers, beginning by saying, 

I’ll lay fourteen of my teeth—and yet, to my teen be it spoken, I have but four—she is not fourteen. How long is it now to Lammastide? (1.3.12-14)

Enjoying the number fourteen, she continues for another fourteen lines until Lady Capulet cuts her off with "I pray thee hold thy peace," and then the Nurse picks up on the word "peace" and rambles about this. In playing her role, the student can take a word and then do the same rambling about it.

• Loving and affectionate to Juliet

As a poor relative, the Nurse has been taken in by the wealthy Capulets to care for their baby daughter. As a result, she has developed a motherly-like fondness for Juliet, although she must also stay in Juliet's parents' good graces lest she lose her position in the Capulets' house. 

When Juliet falls in love with Romeo, the Nurse obeys her wishes and makes contact with Romeo. She demands to be assured that Romeo's intentions are genuine, and she later enables Romeo and Juliet to spend the night together before he must flee Mantua. Even in this serious moment, though, the Nurse cannot resist joking. For, when she says,

I must another way,
To fetch a ladder by the which your love
Must climb a bird's nest soon when its dark. (2.5.77-79)

The Nurse makes a bawdy joke because "climbing a bird's nest" is an earthy expression for having sex.

While the Nurse stands in contrast to Juliet in that she seems more practical than the romantic Juliet, it is yet difficult to understand why she later urges Juliet to marry Paris when she knows Juliet is already married to Romeo: 

Romeo is banished, and all the world to nothing
That he dares ne'er come back to challenge you,
Or, if he do, it needs must be by stealth... 
Beshrew my very heart, 
I think you are happy in this second match, 
For it excels your first, or, if it did not, 
Your first is dead, or 'twere as good he were, 
As living here and you no use of him. (3.5.226-238)

Here the Nurse seems callous towards Juliet, but it may be that she does not want to lose Juliet. For, if Juliet marries Paris, the Nurse will probably obtain a position in Juliet's new household. Perhaps, too, the simple and practical Nurse cannot understand the idealistic thinking of Juliet. The Nurse also could have changed her position because, after her defense of Juliet against Lord Capulet, she has suffered abuse by Lord Capulet and fears for her own safety, having nowhere else to live.

"You are to blame, my lord, to rate her so" (3.5.177) the Nurse tells Lord Capulet, and he lashes out at her verbally, perhaps even physically, as he has demonstrated in Act I that he is rather choleric. At any rate, this is the moment after which the Nurse changes her point of view.