What does the protagonist want? Frank Ball described it as, "The passion the character is desperate to satisfy." The character's objective sort of drives the story. The story after all is about the character trying to reach his goal.
But the fun part is that our hero is not the only character with an objective. Every single character to walk the page has an objective. Their objectives for the most part dictate what they do (while who they and what they've experienced dictate how they do it). And when their objectives clash we have conflict. Like two cars meeting head on, maybe they are going toward the same goal, but for different reason. Or maybe they have two complete different objectives, one to free his friends, the other for world domination (you know, for the ambitious antagonist). And sometimes one objective leads to another and changes upon circumstance.
Dustfinger, in Inkheart by Cornelia Funke, wants to return to his own world. That's his objective. His friend, Mo, wants his wife back, and his daughter to remain safe. But when Capricorn promises to send Dustfinger home, his objective, or desire, to return home is stronger than his friendship with Mo, and so the story begins (in the middle of the action). Now Dustfinger wants the book, Inkheart, and Capricorn's help to return home.
But Capricorn does not want to return at all. His objective is terrorize anyone who crosses his path and become the most powerful man alive (why go for mediocre when you can have an antagonist who wants it all?). So he betrays Dustfinger and makes a show of burning all the books. But Capricorn's objective is to be the most powerful man alive, he keeps one book, because he wants the Shadow by his side.
And the only reason Dustfinger returns is to find the last book. He's a coward, but it's the only way to get what he wants. But he doesn't help Meggie, Mo, or anyone during the ceremony at the end because his desire to return home is stronger than his loyalty to his friends. If he dies trying to save them, obviously he can't return home. So he stays safely away, allows them to save the book, then quietly steals it away.
But Mo's main objective is to keep Meggie safe. That's why he risks his life for her. He wants her safety more than his own.
Other characters' objectives could be an Obstacle for the protagonist.