When a Fictional Character becomes so popular in a series, that the writers are forced to keep them alive until their popularity dies down within the Fan Base.
Man 1: I wish they'd hurry up and kill off Castiel!
Man 2: Sorry, but the Daryl Effect prevents that from happening!
Named after American musician, author, lecturer and Anti-Racism activist, Daryl Davis, The Daryl Davis Effect is when a racially prejudiced/racist person stops being prejudiced/racist towards a certain racial group after spending a lengthy time with a member or members of that certain racial group. Daryl Davis is said to have befriended and convinced over 200 members of the Ku Klux Klan to leave the white supremacist hate group over the last 30 years.
My brother left the KKK because of the Daryl Davis effect after he fell in love with a black girl during his 2 month vacation in Miami.