I need help writing a letter of complaint from Macbeth's perspective of the problem of Banquo's son becoming king...
Macbeth would argue that Banquo and his children have no claim to the throne. As Thane of Glamis, Macbeth outranks Banquo. He also gets a promotion to Thane of Cawdor, but Banquo is not promoted. Malcolm and Donalbain are Duncan's sons, so they deserve the throne, but Banquo does not.
I think I would concentrate on several complaints Macbeth might have. First, he was the next in line to be king until Duncan surprises everyone and names Malcolm his heir. However, Duncan was old and may have been suffering mentally from the affects of age. Macbeth had also fought valiantly against the enemies of Scotland and defeated Macdonwald. As a reward, Duncan had given him Macdonwald's prestigious title, "Thane of Cawdor". Macbeth is a seasoned veteran of many campaigns while Banquo's sons are young and virtually untested in battle. Because of his ability as a warrior, he is respected by other Scottish noblemen. In addition, he has been told by "supernatural powers" that he is destined to be king before Banquo's sons.