Look at some examples— in the Game of Thrones books, one character loses his sword hand, another most of his nose, another several fingers and toes. Well, that’s a bloody violent series. What about children’s books? Harry Potter has his parents murdered because of an evil wizard who was really targeting Harry, and in the Hunger Games, Katniss, the breadwinner of her impoverished family, feels compelled to volunteer for a combat to the death in order to spare her younger sister from that fate.
Even in the mildest of Amish romances, the Lead character will suffer. Perhaps she’ll find her intended kissing another girl behind the barn— or perhaps he’s discussing complicated Bible passages with her. Maybe the Bible discussion would be worse. Or perhaps she’s suspected of stealing something or of doing something that could get her shunned. Even in a mild romance, life isn’t all roses.
The reason for that is that crisis helps us identify with the Lead character and his struggles. Maybe we don’t really care whether Jordun Bigmuscles ever finds that magic sword. But we’ll care when he’s tortured by a wizard— particularly if he gets tortured because he’s saving someone else from that fate. We care if his brother or his mother is killed by his particular enemy— and we perhaps identify with his attempts to get justice. And this identification with the character helps us identify with the rest of the Lead character’s quest.
Each genre and sub-genre has its own rules for what level of character-torture is permitted. In an Amish romance, Lead character Bethany’s enemy is more likely to steal her apple pie recipe than to lop off her arm with a sword. And Mommy and Daddy don’t get murdered in a baby’s picture book. In other genres like spy novels or epic fantasy, a lot of character-torture is permitted.
One caution before you go too far, though. Really extreme events— your Lead character getting his eyes gouged out and his limbs amputated— can take you to the point where the reader stops identifying with the character because it’s just too painful. I know a nurse who quit watching The Walking Dead the time that Bob was captured by some guys who cut off his leg and ate it. If you want a wide readership, you have to restrain your natural sadism a little.
What bad things are happening to the characters you are working with right now? Are you harming them enough? Remember, no one reads books where everyone is happy about everything right from the start. There’s nowhere to go from complete bliss.