Gigi is the daughter of Christopher Hayden and Sherry Tinsdale and Rory's half-sister. Christopher learns that Sherry is pregnant while at Sookie's wedding with Lorelai. Christopher and Sherry had been having relationship problems, and he had planned to break up with her. However, when Sherry calls him to tell him she's pregnant, he decides to go back to her. Gigi is born in 2003.
When Gigi is almost two, Sherry leaves Christopher and Gigi to take a job in Paris. Christopher spoils Gigi, and she is so bratty that Christopher can't keep a nanny or get Gigi into preschool. When Lorelai babysits Gigi, Lorelai tries to be fun and exciting but Gigi acts like a brat. After Lorelai babysits Gigi, she confronts Christopher about his parenting. He takes Lorelai's advice, and Gigi becomes much better behaved. After two years, Sherry apologizes to Christopher for leaving him and Gigi and says she wants to be part of her daughter's life again. Christopher and Lorelai accompany Gigi to Paris to visit Sherry, and Gigi stays with her mother for several months. While in Paris, Christopher and Lorelai spontaneously get married. When Gigi returns from Paris, she lives in Stars Hollow in Lorelai's house, and Rory's bedroom becomes Gigi's room. After her father and Lorelai fight over a letter Lorelai wrote for Luke's custody battle, Gigi and Christopher stay at his mother's house. Christopher and Lorelai subsequently divorce; Gigi is occasionally referenced by her father and Lorelai, but she doesn't make any more appearances.
- Dear Emily and Richard • Norman Mailer, I'm Pregnant! • Emily Says Hello • Come Home • Bridesmaids Revisited • Partings • The Great Stink • French Twist • Santa's Secret Stuff