Make them fall.

Make your characters fall.

 Make them bleed. 

Make them cry. 

Make them hurt.

Anything. 

Think about the last book you read. Did the main set of characters never get injured? Or get hurt mentally or emotionally? Did they cry at any point? Even if nobody but you saw them cry? Did they? No? Lies. 

Every protagonist or main character within a story needs to experience pain of some kind. Physically. Mentally. Emotionally. It could be little or large, small or big, but it needs to happen in order for them to learn and grow as a character. 

Physically: stabbed. Shot. Punched. Kicked. Bruised. Bleeding. Brink of death. Burnt. Almost drowned. Water boarded. All of these are physical pains that your character could experience. Not all of them of course but perhaps a couple of them. It gives them something to overcome and something to get around in order to move themselves and the plot forward. 

Mentally: Psychotic break. Depression. Anxiety. Social recluse. Psychotic. In short, mentally troubled. This could happen through torture, the incorrect balance of drugs. A traumatic event that's been suppressed. Something that cannot be physically felt or seen. Neither can it be helped through comfort or be felt as being 'normal'. 

Emotionally: Hurt. Betrayed. Deceived. Upset. An emotional wreck. Let's pretend you have two best friends for characters. One of them dies. Here is the emotional pain that they have to experience and work through. It is something that they have to come to terms with, something they have to figure out is acceptable or not, until then they are emotionally invested in the wrong thing. 

But if your character does not suffer in any shape or form. If they could go into a gun fight, with a knife, screaming and yelling head first, and come out of it unscathed, their limbs intact and all of their blood still inside of them, then they are not believable. They appear to be superhuman as they defy the odds. That is not the kind of character a reader would like to read about. 

The human race has a sick fascination in fiction of reading what other people suffer and finding some form of mild enjoyment from it. Now I'm not saying we're all some sort of sick and twisted murderer or kidnapper, but in fiction we take delight in reading that somebody is hurt just to see how they get out of the mess. It is this anticipation that keeps your story going and keeps the reader hooked. 

Make them fall.