What’s your motivation?

A few months ago, I read Brak the Barbarian, a sword and sorcery novel by John Jakes, now best known for North and South. I’d read the later novels in the series back in my teens and hadn’t been impressed; reading the original novel (actually a collection of linked short stories) I was surprised how much I enjoyed it.
Rereading the second Brak novel, Brak the Barbarian—the Sorceress, I’m inclined to think my teenage self was right. The novel is certainly better written than many Conan knockoffs, but Brak is lacking in something Conan was never short of: Motivation.
Conan gets into adventures because he wants things. Wealth. Wine. Women. Sometimes obtained as a thief or a bandit, sometimes as a mercenary. Eventually as a king. When he winds up fighting monsters instead, it’s usually because they’re in the way, or because he can’t get back to the wine, wealth and women until they’re done.
Coupled with Robert E. Howard’s writing—he invested Conan with a real intensity—it makes the Cimmerian more believable than you’d think. As one writer put it, Conan doesn’t win because he’s stronger than anyone else, he wins because he’s tougher and more determined than anyone else.
Brak, by comparison, just gets into adventures because … well, he happened to be standing around when they happened. This wasn’t a big problem in the first book, where he kept running into menaces on his quest for fabled Khurdisan; in this one, where he’s in one place, fighting one threat, it sticks out like a sore thumb. There’s no real reason for him to keep fighting the sorceress Nordica other than … well, the plot needs him to, right?
It’s one of the standard writing-advice messages that your characters have to care, passionately, to keep your readers’ interest. By failing to do so, this book shows why it matters.