worm turns
(idiomatic, usually preceded by the) Circumstances change so that a previously disadvantaged party gains the advantage, or vice-versa.
To revolt is a natural tendency of life. Even a worm turns against the foot that crushes it. In general, the vitality and relative dignity of an animal can be measured by the intensity of its instinct to revolt. Mikhail Bakunin
The worm turns. American Proverb