The worm turns

Cultural  

1. One's luck or fortune changes.

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worm turns, the Idioms  

1. Also, the worm has turned. Even a very tolerant person will one day lose patience. For example, He bullied his assistant for years, but one day the worm turned and he walked out without notice, taking along his best clients. This expression comes from the proverb Tread on a worm and it will turn, first recorded in John Heywood's 1546 collection.

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Example Sentences

As the story’s many twists expose Daisy and Craig for who they really are, they come to understand that once the worm turns, the forbidden fruit isn’t quite so appealing.

From Los Angeles Times

The Ooley-cow was so very easy that they took liberties with him, so good-natured about his losses that they presumed upon that good nature and ridiculed him openly; but the old saw sometimes loses a tooth, the worm turns, the straight road bends at last, so does the camel's back, and the prize cow kicks the milker into the middle of next week.

From Project Gutenberg