Why You Call Me?

Cassian immediately called Theodore when he saw him coming from a distance; he needed to discuss the problems they would face on the second floor later. 

Because of the commotion they caused on the first floor, the zombies on the second floor began to hear the commotion on the first floor, and they began to descend to the first floor. At this time, Cassian made a barrier wall above the elevator leading to the second floor. 

Theodore, who saw Cassian, quickened his pace. When he was next to Cassian, Theodore realized that there was already a barrier wall above the elevator, so he immediately thought something was happening there. 

"Why did you make a barrier wall here? Are the zombies at the top trying to get down?" Theodore suspected the zombies on the second floor were trying to get down to the first floor, so Cassian built the barrier.