Vader's turn to evil, then later back again to being good is a great way to capture the audience because it happens to us in everyday life. In real life we try to be good. But we get stepped on so much that we turn evil out of necessity. Only to pay the price down the road for that decision. And ultimately repent for our deeds in the end.
How many elderly do not repent on their death beds?
It's a wonderful dramatization of true life.

Sort of like the real-life stories that one hears about from time-to-time of the convicted rapist who risks his own life to save a drowning child........or of the convicted murderer who rescues several people from a burning building.

Such things happen. And such are the inconsistencies of that desolate and raging wilderness known as human nature.

Something To Do At 3:00AM