Luke's forgives Vader
Following the meeting with the temptress, the meeting with the father is the next step along the hero's journey. This is the center point of the journey, and all the previous steps the hero has taken along their quest have moved towards this moment. It is now that the hero must confront and be initiated by whatever holds the ultimate power in his or her life. In many myths and stories this is the father of the hero, though it does not have to be a male; just someone or thing with incredible power.
Professor Joseph Campbell: "Atonement consists of an abandonment of the attachment to ego itself, and that is what is difficult. One must have a faith that the father is merciful, and then a reliance on that mercy. The problem of the hero going to meet the father is to open his soul beyond terror to such a degree that he will be ripe to understand how the sickening and insane tragedies of this vast and ruthless cosmos are completely validated in the majesty of Being. The hero transcends life with its peculiar blind spot and for a moment rises to a glimpse of the source. He beholds the face of the father, understands—and the two are atoned."
This central step is all about acceptance. Acceptance of the fact that the universe in all its chaotic madness and glorious reason is bound together in an indestructible whole. In making peace with the father, who in the story can be an actual parent, a god, or something inside the hero's own head, the hero is accepting that which they have striven against for the first half of their journey.
In many myths, parental figures represent the need for the hero to break free from childhood into adulthood. The father figure may be portrayed as threatened by the rise of the hero and so establishes a horrifying conflict. The hero seeks "at-one-ment" with the father, having faith that they are merciful. In turn, the father undergoes a change of heart and the fearful image dissolves, releasing the hero from peril through reconciliation, forgiveness and mercy. Just as the mother may be portrayed as good or evil, so can the father figure, the contrast representing the dual role of the parent that the hero must accept and become.
If the meeting with the goddess represents the acceptance and unification of the disparate parts of our emotional being, then the meeting with the father represents our understanding and acceptance of our thoughts. In other words, after atonement with the father, the hero ceases to wonder why they suffer. They learn to see that which they saw before as "negative" as an expression of the divine spirit just as much as the blessings they receive. We tend to search for some kind of explanation for misfortunes like illness, disaster, poverty, and death. Myths teach us that the reasons of the divine aren’t necessary for us to know, and that we aren't plagued with such things because we did something wrong. Perhaps the wisest we can do in the face of such disasters is calm ourselves by recognizing them as learning experiences because they certainly help us grow.
The trials that the father puts the hero through are meant to ensure that they’re mature enough to handle greater knowledge and power. Thus the hero undergoes a rebirth, from one who depended on rules and lessons from past authorities to one who gets full permission to violate those rules and lessons as well as take full responsibility for them.