LUKE: There’s nothing to think about. He’s family. You take care of family, period.
LORELAI: Yes, I respect that, but what if he turns out to be Fredo?
A reference to the film The Godfather Part II, the sequel to The Godfather, previously discussed.
In the films, Frederico “Fredo” Corleone (played by John Cazale) is the middle brother in his family. He is seen as a weak person, with little power or status in the crime family, and given relatively unimportant jobs to do. During the course of the film, his younger brother Michael, who has become the Mafia don, discovers that Fredo betrayed him. He has Fredo killed.
Before Lorelai even meets Luke’s nephew, she is prejudiced against him, and makes none-too-subtle hints that the boy is a petty criminal who may not be worth helping.