The brothers were pacing around the compound after being shooed away from the room by their uncle Hades. Arcus and Zargreus did not particularly want to leave because they thought they could be some kind of assistance to the older god but the look in his eyes when he shouted told them what was about to happen was way beyond anything they could help with. So they left him to work but not being in that room made the anxiousness ten times harder as they went their separate ways.