One way to grab, and keep, your readers’ attention is by letting your characters have contrasting attributes in their personalities.

I’m not speaking of your story’s plot containing a twist or having a surprise ending. I mean conflicting qualities within a person.

Here’s an example:

One of your characters runs a children’s charity. But he also has a terrible temper.

Of course, under the well-known “show, don’t tell” guideline we want to show contrast within a character rather than tell it. So in the example above we’d write:

“Matt runs a charity that has raised more than $500,000 for children's causes,” John said.

“Yes,” said Bill. “But I’ve seen him beating his own children.”

That contrast between the two sides of your character makes him a compelling one.

Usually, we need to introduce contrast with a word or phrase. I wouldn’t have written above:

“Yes,” said Bill. “I’ve seen him beating his own children.”

That doesn’t make sense because Bill appears to be ignoring John’s comment about Matt’s charity. So instead we need to add a transition between the two sides of Matt’s character, and that’s what the word but is. Here are some useful terms to introduce contrast:

          on the other hand, however, but, nevertheless, still, on the contrary, in contrast, or, nor, yet, one/another difference, conversely,
          unlike, whereas, then

It doesn’t matter too much which of these terms or phrases you use, as long as it makes grammatical sense and your reader knows you’re about to transition to a contrast. In the example above we could have used however as our transition word. That would have worked just as well.

The possibilities of contrast within your characters are endless:

      The minister who’s sleeping with his secretary
      The police officer who’s associated with organized crime

All of my examples so far could be considered a negative contrast. That is, characters who outwardly appear to be good people have decidedly undesirable attributes. But it’s just as effective to write about unsavory characters who have noble sides.

You could create a character who chases off any neighborhood kids who dare to approach his home. But he also gives thousands of dollars to children’s charities every year.

And here’s another way to further this idea of contrasting attributes: write about why your character has these divergent qualities. Perhaps in the example above your character runs the neighborhood kids off because his own now-grown children don’t keep in touch with him. That makes his resentful of children. Why then does he give to children’s charities? Because the kids he helps send him Christmas and birthday cards, unlike his own children. Contrast like that makes your character compelling.

One of my favorite writers, British veterinarian James Herriot, was a master at showing contrast within his characters. One man he wrote about was sloppy in appearance, an indifferent parent, and in general ran his personal life poorly.

But the man cared deeply about his animal patients. That contradiction made the character memorable.

Along a similar line, don’t hesitate to have a character act outside his customary personality on occasion. Even if your character is entirely evil, let him perform a good act. Or have a character who’s upright commit a crime. Again, the idea is that you’re bringing in contrast, and your readers will enjoy that.