|Being between Scylla and Charybdis is an idiom deriving from Greek mythology, meaning "having to choose between two evils". "Between a rock and a hard place" express similar. Scylla and Charybdis were mythical sea monsters on opposite sides of the Strait of Messina between Sicily and the mainland. Scylla was described as a six-headed sea monster on the Italian side of the strait and Charybdis was a whirlpool off the coast of Sicily.|
Avoiding Charybdis meant passing too close to Scylla and vice versa. According to Homer, Odysseus was forced to choose which monster to confront; he opted to pass by Scylla and lose only a few sailors, rather than risk the loss of his entire ship in the whirlpool.