In the first-season episode " Inner Child " (S1E15) of the sci-fi series Fringe , the team investigates a mysterious child found in a long-sealed underground chamber who helps locate a serial killer. Walter Bishop suspects the boy might be a young Observer, a recurring entity in the show, and this episode features a neural halo later seen in the series. You can explore the details of this episode at Inner Child - Fringe Connections and Fringe Episode Review: Inner Child . Inner Child - Fringe Connections