scapegoat
n
(also esp US fall guy) person who is blamed or punished for the wrongdoing of sb else 替罪羊
I was made the scapegoat, but it was the others who started the fire. 是别人放的火, 让我背了黑锅.
There has long been a superstition among mariners that porpoises will save drowning men by pushing them to the surface, or protect them from sharks by surrounding them in defensive formation.