Constans paused in the middle of throwing the already-organized shelf into absentminded disarray, glancing back at Bethen with a frown upon being shushed. Both slightly affronted and amused that she had actually, literally 'shushed' him, he strained his hearing when posed the question. At first nothing but the dull, hollow quiet of the cavern came to his attention, but just as he was about to make another smart-mouthed comment, there was a faint... something. It sounded like- like slithering?
"Ya-!" Constans yelled incoherently, startled by the sudden explosion of noise. Bethen's following comment coaxed an embarrassed laugh from the young man, a defensive cover for his wounded dignity. "Haha- er, hey, you know I was kidding?"
While she scurried to look, Constans ran a hand down his face and shook his head at his own foolishness. Trying to dismiss the jitters triggered by his sudden shock, he stuck his chest out, slapped a self-confident smirk back onto his face and strode over to join Bethen. There couldn't really be anyone in here, could there? They were in a locked, no-admittance underground cavern, beneath a lake. The very idea was a bit ridiculous. Maybe there was a badger or something, at worst? Some kind of burrowing, hibernating animal, waking for the spring.
But then again... badgers didn't make slithering noises.
"Nope," Constans declared, frowning down the empty, dim corridor between shelves, unable to make out so much as a twitch. "Magical sneeze. Definitely."
Dropping his volume he added, "If you go around that way," he gestured right, to the narrow walkway between the rows of shelving units and the wall, near the egress to which Bethen stood, "I and I go this way," he pointed down the dim corridor before him, "supposing that there's anything there at all, we could trap it. Him. Whatever it is- but, I note, probably isn't because it's insane that anything could get in here, you realize that right?"