Knowing my characters.
Usually they are people that I see across in a bus a train or some public place, I tend to step into their world or rather stumble into their world the way it occurs to me.
But yes, there is plan, and a plot. I plan to share something through a plot.
Recently I came across an writer who said, she makes her characters fascinating by developing three essential components, to their personality, their core need, their greatest fear and the lie they tell themselves maybe somewhere it is a core, but to me I would like my character to manifest with a little more positive.
I really do not worry too much about why someone does something more than how each person has perceived the event and my protagonist.
Say I am telling a tale of three brothers, from western tales I would probably look at what makes son one the way he is, son 2 the way he is son 3 the way he is more to fill in the word count. But off the three brothers my story would be the story of one of the brothers and of, how he perceives the story of the other two.
Of course conflicts do arise. After all it is the conflict that creates the drama.
With an underlying stream from common stories or mythology the juxta positioning gets spiced.