Despite the tense situation and having to walk in poorly lit darkness, several kilometers below ground, Braxton, Hal, and Wyrie tried to lighten the mood a little. Everyone was understandably feeling anxious due to their mission and the risks involved, so their efforts were appreciated even if they weren't that successful.
The efforts to keep the mood light and at least somewhat cheery were most effective during the first half of their walk. But the further along and the closer to their destination they came, the more somber everyone became.
Toz and the others weren't needlessly overcome with anxiety. But since the mission was so dangerous and vital to the war, everyone wanted to get in the right headspace. They went over the details of the plan several times in their heads and prepared themselves mentally for whatever they might face.
Toz, Braxton, and Seich also stayed vigilant about their surroundings.
