How does Shakespeare present Macbeth as a troubled character?

One way in which Shakespeare presents Macbeth as a troubled character, is through his constant and overarching insecurities, with reference to his, illegitimate, authority on the throne of Scotland. These insecurities become an overwhelming feature as the play progresses, and so help to build our understanding of Macbeth’s continual mental deterioration as a result of his brutal rule. This is demonstrated at several pivotal moments within the play, including the beginning of Act 3, Scene 2 - in particular, when Macbeth says that he and Lady Macbeth have “scorched the snake, but not killed it”. This is one of many, almost zoomorphic references to animals throughout the play. Though the use of "snake" here is marked because snakes are typically associated with coldblooded characteristics which are undesirable at best and repugnant at worst. This partnered with the biblical allusion of the snake’s temptation, which led to Adam and Eve being expelled from the Garden of Eden, and the use of the snake as a repeated motif throughout the play, can lead us to conclude that it is being used by Shakespeare to demonstrate Macbeth’s lack of trust in his people. This, in turn, implies that Macbeth is insecure of his status as king, as the witches foretold, and thus, he fulfils the role of a troubled character who will never be entirely secure. Furthermore, the sentence structure used in this passage of speech adds to the complexity and troubled nature of Macbeth’s mindset. In particular, there are two mid-sentence full-stops after “nightly,” and “ecstasy,”. This unusual sentence structure which forces the actor to pause midline, and so breaks up the perfect tempo created by iambic pentameter, draws our attention to what is said directly before and after; in both cases, it is the ‘after’ sentence, which is more critical. With specific reference to “ecstasy,” which is followed by “Duncan is in his grave.” the short sentence created by the latter, emphasises the statement, and thus conveys both the weightiness of such an assertion, but also reminds the viewer of this performance, and even Macbeth himself, of what he has done. Thereby grounding his current emotional turmoil, further created through the varying metaphors, such as Macbeth's proclamation that his mind is "full of scorpions", and histrionic language, as shown by Macbeth's fear of "restless ecstasy" in his prior actions, and so allows us to conclude that, perhaps, Macbeth is trying to convince himself that being dead is far better than being alive because his friend is about to be killed by his hand. By interpreting the play in this way, it can be understood that Macbeth is in insecure about the upcoming assassination of his friend, and so is emotionally and morally troubled by his own actions. However, it can also be argued that Macbeth remains profoundly assured that he is meant to be on the throne, and thus is not controlled by these insecurities, and so, is perhaps less troubled than first considered. Support for this argument is Macbeth’s final speech before his death. Especially, his claim “yet I will try the last.” The modal verb of "will" expresses a determined declaration of his intent to fight Macduff, ultimately to death, and emphasises his deep-seated resolve to remain, as foretold by the witches, on the throne of Scotland. Therefore, perhaps implying that Macbeth is not a troubled character, but merely one that undergoes and truly irredeemable transmutation throughout the play. Nevertheless, whilst that is a tempting interpretation, the most compelling argument, is, undoubtedly, that Macbeth is a troubled character. The reasoning for such is that much of the structural nature of the play revolves entirely around Macbeth’s self-doubt and uncertainties, which lead him to become a troubled character.