What's the difference in timing between these two statements?
- He made dolls.
- He had made dolls.
It's pretty subtle!
Let's try changing just the simple tense from past to present in both lines, and see what they say.
- He makes dolls.
- He has made dolls.
What if we change the simple tense to future?
- He will make dolls.
- He will have made dolls.
When we use had/has/have to show completed action, we're emphasising the end of the action—the moment where it goes from "not done" to "done"—whether or not that final moment has already happened in the past or will happen in the future.'
Let's tie this to narrative writing!
In narrative writing, we often use simple past tense (with no tense helpers) and completed action to help establish a sort of timeline for the characters: Julia came, then she saw, and finally she conquered.
Since most narratives are written completely in the past tense, the simple past makes it seem like the action is happening to the characters as we read.
That then means that using completion in the past tense tells the reader the action happened further back in time relative to the characters in the story: Julia came, then she saw, and finally she conquered—just as she had promised her father when she was a litle girl.