The worm will turn
Definition 1 of 1
Pro Tip 1/3Unexpected Change
This phrase highlights a surprising shift when the meek or disregarded person takes action. 
His patience ran out, and the worm will turn, shocking everyone with his bold move.
Pro Tip 2/3Metaphoric Worm
Remember, the 'worm' represents a person, not an actual worm. It’s a metaphor. 
Just when they thought she would comply forever, the worm will turn.
Pro Tip 3/3Emotional Context
Use it to empathize with someone’s limit of tolerance before they push back. 
They underestimated her once too often, and the worm will turn.