Well the shock of Eight's immediate answer gets completely overshadowed by the floor rumbling under his feet and then the door cracking?? He jerks a step back, eyes widening enormously. His body goes tense, preparing for a fight.

"What-- you--" he makes these few startled noises, and then Ten's voice behind him focuses his thoughts. He steps to the side to the monster can see the door splitting like that, and he gestures wildly at it.

"There's something in there??" Something's in there or it's Seven, and his voice makes it clear he has no idea which it is, jerking back another step as the door continues to break outwards towards him.