"I have found that a story leaves a deeper impression when it is impossible to tell which side the author is on."
~ Leo Tolstoy
I remember worrying as I read the last few Harry Potters, wondering who Rowling was going to kill. No one felt safe. After Dumbledore's death, I believed Rowling was capable of killing anyone - even Harry. I fretted about Hagrid, about Ron and Hermione, about Luna and Neville and Lupin...I was both eager to know what would happen next and terrified of what it might be.
THAT is powerful storytelling.
We need to remember to allow ourselves to be unpredictable as authors - to do the unexpected. What could you do in your story that would be so unexpected the reader no longer trusts you to keep your MCs safe? To let your MCs be happy or healthy or loved? Bold writing, risk taking, makes for a more emotional read..
As you write today, do something unpredictable.