What are some Relevant Themes in the Play/Book (Romeo and Juliet) that I could use to Create a 20-Line Freeverse Poem for school?

You could perhaps continue with the sonnet prologue? "Two households" etc,?  Or take a particular dramatic scene, the death of Mercuto for instance, and develop that, or the killing of County Paris at the Capulet tomb? All this sounds maudlin, and I apologise, however, there are other scenes you could develop, the nurses happy meanderings on Juliet as a girl? The banter between Mercutio, Benvolio and Romeo which leads to the Queen Mab speech? But, please excuse me for asking, why twenty lines?