Book 2 Chapter 2 "THE CAVE OF TWO LOVERS"

While on the way to Omashu, Aang and the group meet a group of carefree traveling bards, who take them through a vast tunnel known as the Cave of Two Lovers. Zuko and Iroh are sheltered by kind villagers after Iroh accidentally drinks tea made of a poisonous plant. Song, a young and compassionate healer, shows Zuko the effects of war from a normal citizen's perspective. The group is separated in the tunnels by a cave-in, with Aang and Katara growing closer as they discover the origins of the cave, which includes the tombs of the first two earthbenders, who are the namesake of Omashu. Their torch burns out, plunging them into darkness and eventually resulting in a kiss. Glowing lights are revealed in the ceiling, allowing the group to escape and make it to Omashu, which they discover has been conquered by the Fire Nation.