fish in troubled water 混水摸鱼；浑水摸鱼；趁火打劫

【例句】
A man of good character will not fish in troubled water.
一个高尚的人是不会浑水摸鱼的。

And there won't be lack of flunky who fish in troubled water to lead to dark reality.
混乱就不会少了浑水摸鱼的小人，来造成黑暗的现实。