Before I begin, I would like to warn any potential reader that this post will contain spoilers, especially if you have never read Macbeth.
The fourth issue of Toil & Trouble begins directly with a reference to Shakespeare's Macbeth. Our experience with the previous volume would place us directly after Act I, Scene 5, and so, while the first two pages orient our view of this new narrative, our place with respect to the hypotext (Shakespeare's Macbeth) is confirmed in this, the third page, wherein Duncan and Banquo speak of Macbeth's castle. The specific choice of words here is what finalizes the connection between the texts; the king distinctly says that Macbeth's "castle hath a pleasant seat" and is replied to by Banquo with talk of martlets.
In the hypotext, the martlet is a mistaken good omen which lends irony to Duncan's (and eventually Banquo's) impending death. Our knowledge of this poor augury allows Scott to show us how she intends us to interpret what they portend; they represent the innocence of the children buried. Cait understands that the birds are not attracted to sweet air, but the sweet innocence of the ghosts of many children who had met their untimely demise here. It is a terrible omen, one befitting a tragedy.
Finally, we have the dagger scene. In the previous page (I do not show it only due to the fact that there are multiple pages in a row that show a relation to Shakespeare - I haven't enough space), we are able to see Macbeth speak his famous lines: "Is this a dagger I see before me?" He continues with a direct quote in this page. The previous pages show Lady Macbeth's hesitance to kill being caused by Riata, her inner turmoil caused by an external sources rather than internal. Here, we see the same with Macbeth. Where Shakespeare's characters became impossible to relate to in their ambition, these characters continue to earn our empathy when their ambition and paranoia, and the actions that create it, are no fault of their own. Scott is turning the hypotext's story into a modern tragedy - Macbeth's greatness is his humanity, and his loss of it, along with the subsequent realization of this fact, is what will create Aristotle's catharsis. As a modern audience, we no longer care for Macbeth's station and reputation so much as we care for his inner peace and morality.
As a counter-point, we see a mirror image in the witches as they slowly lose their humanity, their governing rules, and their own morality as they begin to fight each other behind the scenes. Even the colouring on the page reflects the conflict - Riata's red against Smertae's blue. We know whose plan prevails in the end - Riata influence on Macbeth allows him to gain the throne for a time until Malcolm, the one she advocated for from the beginning, eventually takes his throne back. This implies that Smertae loses in some way, but we have no idea what that entails. That is what makes Toil & Trouble so interesting, so foreboding.
An interesting thing to note about this (so far) unresolved conflict is that neither side will be eliminated. Or can they? After all, every witch but Hecate, a Greek goddess that has a high likelihood of behind left out of the hypertext, is nameless in Shakespeare's tale, and so the addition of other witches may occur. However, that would involve the resolution of Toil & Trouble before the resolution of Macbeth, which cannot happen since the resolution of Macbeth is promised to us, the readers, by the nature of the woven narrative between hypertext and hypotext.
Our knowledge of the hypotext, then, betrays us. We create expectations based upon the hypotext and, with those expectations we create a rudimentary direction for the hypertext to follow. It is this betrayal that lends this form of transtextuality so much power - the deviations in the path surprise us and compel us to continue reading. We know where Macbeth ends up, and his tragic story (though with modified emphasis) sets our expectations and generates familiarity - the unfamiliarity of the witches, and the unresolved tension between them, keeps us reading, keeps us invested, as we attempt to determine how we arrive at Act IV, and how the witches, who never appear afterward, finish their part of the story.
-Stephen St. Louis