In the episode (Season 2, Episode 20), the usual high-stakes sci-fi of Fringe transforms into a drug-induced noir musical told through the eyes of a grieving Walter Bishop. The Tale of the Glass Heart
: Walter's version of the story ends tragically, with Peter leaving him forever—mirroring Walter's fear that the real Peter will never forgive him for his past actions.
Desperate and high on his own potent marijuana strain, "Brown Betty," Walter tells Olivia’s niece, Ella, a fairy tale to pass the time while Olivia is away searching for the missing Peter.
: Walter is a master inventor who claims to have created the world’s "good things"—bubblegum, hugs, and rainbows. However, he is physically dying, kept alive only by a chest full of batteries.
: In the noir world, they are "The Watchers," ominous figures with rayguns that "burn through flesh".
For a deep dive into the script or specific lines, you can view the full transcript on Springfield! Springfield! . TV Review: Fringe, Season 2, Episode 20: Brown Betty
