Vaan had chosen to stay outside of the dungeon to serve as Alex's eyes and ears.
Perhaps there was no one more wary of Demon Worshipers than Vaan because he had lived a few years under Willow's control.
Truth be told, he had developed an innate fear of them. Before the expedition, he had confided this to Alex.
As such, Alex had decided to let Vaan stay outside the dungeon so that he wouldn't have to fight against the Demon Worshipers directly.
After seeing the Demon Worshipers that the Headmaster had subdued, Vaan recalled the horrors that he experienced back then.
However, since he knew that fighting against them was inevitable, he steeled himself and looked at them so that he could develop some kind of resistance against them.
Although his face had turned pale and his body would shudder from time to time, Vaan clenched his fists and refused to look away.
Alex had jokingly told him something a day before they went to the dungeon.
