Paris Eustace Geller is introduced in the second episode of Season 1. The child of wealthy, Jewish parents, she was raised almost completely by her Portuguese nanny. Paris was originally Rory's arch-nemesis at Chilton Academy, partially because she felt threatened by Rory's academic prowess, but more because of the attention that Tristan Dugray (Chad Michael Murray), the local golden boy/bad boy, paid the new transfer from Stars Hollow High. Her two best friends prior to Rory were Madeline and Louise, who were more concerned about boys and makeup than Paris' focus on her academics. Paris starts a relationship with a Princeton man, Jamie (Brandon Barash), which ends after Paris starts an affair with a Yale professor, Asher Fleming (Michael York). The affair ends when Asher dies. Paris starts to date the Yale Daily News editor Doyle McMasters(Danny Strong) and eventually moves in with him. Paris attends Yale as well and is roommates with Rory for all four years, and is finally accepted into Harvard Medical School. Paris is consistently nervous about meeting standards and is often angry when annoyed, having an extreme Type A personality.

Paris was originally created for a three-episode guest arc by series creator Amy Sherman-Palladino and executive producer Gavin Polone at the beginning of the show's first season to introduce Rory Gilmore's character to the high pressures, competitiveness and stress of going from the small public high school in Stars Hollow, to the storied and respected halls of Chilton Academy. This character was created in consolation for Weil after a strong audition for the role of Rory, which eventually went to Alexis Bledel. Weil however had to change her hair color to play Paris from her natural brown hair coloring to blonde. This was done to further the contrast of Paris to Rory. The character proved to be the proper foil to Rory in time, and the role of Paris in the show was extended and expanded through the first season until Weil became a series regular in the second season.