Motives can be pretty basic - characters want money, status, love, sex (not necessarily the same thing as love!) and so on. But there can be other motives - a desire to show those who put you down years ago you are something special (The Ugly Duckling springs to my mind here though in his case there is also a desire to belong, which thankfully is eventually fulfilled).
The thing above all else to get right is that the motive for the character has to ring true for the reader. That is the reader quickly finds out who your character is and can figure out yes, a character like that would want this or that.
Motives can be hidden, they often are in crime novels until close to the end. You can leave readers wondering what a character wants but I would drop hints periodically as to what the character is likely to want. I know as a reader when I come across this, I like the guessing game and love it when I'm right. I'm even more thrilled when I guess wrongly and the author has come up with something here that didn't occur to me (yet when I look back through the story, the clues were there). If you are going down this route, you still need to work out what the driving motive is before you can think of "covering it up" until the proper moment in the story to reveal it (and it must be revealed at some point).