How does Shakespeare explore the theme of fate in the prologue of Romeo and Juliet

The Prologue is a key element in how our expectations of the outcome of the tragedy of Romeo and Juliet are handled. The Prologue, which was often delivered by an authorial character (see Gower in Pericles, Quince in Midsummer Night's Dream) served to establish audience expectation in Shakespeare's theatre for an audience with few preconceptions of this individual story but a complex understanding of the tropes of Renaissance tragedy. By describing the fate of the "star-crossed lovers" at the beginning of the play, the Prologue suggests that it is fated that they will "take their lives." The struggles of Romeo and Juliet take place within a dramatic irony that is created by the Prologue - when Romeo claims to break free of fate by exclaiming "I defy you, stars" we cannot but help be reminded by the Prologue's prophesying. Furthermore, the Prologue is written in a sonnet form - the form that Romeo gradually adopts more and more in his speech. Fate, Shakespeare suggests, is formal - the more Romeo denies his fate, the more he accepts the form that fate has created for him. But it is important to note how Romeo and Juliet plays with audience expectation, as well as establishing it. Despite being presented by the facts of the narrative, when we first meet these "star-crossed lovers" they are not lovers at all - Romeo in fact loves another woman, and Juliet is betrothed to Paris. Even "take their lives" is open to interpretation - it could mean suicide, but also "taking life from"/being born from the warring houses. These different possibilities in interpretation mean that Romeo and Juliet is a tragedy of different possibilities - perhaps, this time, the narrative will play out differently. Only a piece of theatre could be this flexible. We know the text of Romeo and Juliet itself did change across performances - there are three different versions of the text existing in print, and the play could have been adapted for smaller touring companies in Shakespeare's day. Returning to the Prologue, it is important not to ascribe too much authority to this figure. He might stand in for the author, but often prologues and epilogues were separate documents to the rest of the play and may have been written by another author. Prologues in particular were not even performed with every performance, often only standing for the first performance where an audience could "damn" a play they did not like. There have been adaptations of Romeo and Juliet where there is a happy ending - in particular, Davenant's 17th century adaptation. So whilst Romeo and Juliet's story might be fated to end in the form the Prologue has given it, it is performed in an environment which is flexible, and is full of alternative possibilities.