inform: to give evident substance, character, or distinction to; pervade or permeate with manifest effect
When we write out scenes, we know what each character's objective is in that scene; we know what their "want" or "need" is. Additionally, we know each character's backstory: their hobbies, upbringing, family, and all the other things that have brought them to this moment in time.
Therefore, all that stuff must inform their dialogue and actions throughout the rest of the book. For example, if Sally-Ann was molested by her stepfather as a pre-teen, then all of her interactions with boys are going to be colored by that past. If Jose's parents illegally crossed the border right before he was born on American soil, then this will influence how he interacts with other kids whose parents have never set foot in Mexico, even ten or twelve or fifteen years later. If Bethany's Daddy has always given her whatever she wanted and now her daddy has disappeared, then she will react differently to his disappearance than if he had never really been around to begin with. All that stuff that happened long ago in your character's history, while it shouldn't necessarily be stated outright, should still be "there" somehow. It needs to inform everything that you put on the page.
I'm not saying that you need to create caricatures, or that you should make everything spelled out and predictable. But I am saying that when you write, you need to always think about whether this is your character talking, or you talking; whether this is a curve ball that is there as a plot device, or as a genuine reaction from your character.
Let his or her past and needs inform what they do in the present moment. This keeps the reader grounded, and keeps your characters consistent.
How have your characters' intentions informed their actions?