noun
plural -tages
[count] :a person who is captured by someone who demands that certain things be done before the captured person is freed
a hostage to fortune
In British English, a hostage to fortune is something (such as a promise or an action) that someone has made or done that may cause problems in the future. In U.S. English, this phrase is much less common and is usually understood to mean a person whose future success or failure is controlled by luck or fortune.