Furthermore, Reagan and Goneril acted unnaturally when they disowned their own father and fought each other over a man. Both women were not just or virtuous leaders, so it makes sense that their fate caused them to fight, and ultimately ruin, each other. But they couldn't possibly have had that fate determined when they were born, so is it possible for one's fate to change based on their actions, or are all of their actions based on their fate? It seems like one's fate may be adjusted at some point. King Lear was almost punished for the unfair treatment of all of his daughters. He favored Cordelia, so his other daughters were less inclined to put up with him in his madness. So maybe because King Lear sent away the only daughter who cared about him, he was punished.
Though fate is less openly discussed in this play, it definitely plays into the characters' lives. One could reason that Cordelia was sent away to teach her family, and the rest of society, a lesson. When people go against what is natural in their lives they will be punished. What is natural is fate. When people try to stray away from their fate, and any natural order, their fate keeps them in line. Though Edmund wanted to be powerful, he was not meant to be; his fate kept him in line when he strayed from the path. By creating unnatural situations, banning Cordelia and betraying family, circumstances worsen until the perpetrators regain focus and begin to follow the right path again. Unfortunately, this pretty much ends with death in this play. So the play reiterates the idea that fate cannot be tricked or changed. It is comforting, though, because if we follow the natural path we are meant to, fate will be pleasant and everything will end up right in the end.