As Sephiroth entered the ruins, he took a long, lingering look around before stepped any further across the watery floor. As others went about interacting, discussing and even summoning a somewhat-small eidolon in their efforts to decipher any secrets the room held, Sephiroth went about patrolling the perimeter; paying special attention to how deep the water was each time he put his foot down, tracing as best that he could imagine where the walls would have been before the whole place fell to the sorry state that it's in.

The damp air makes it feel close, yet that might be down to his imagination as he's mapping out in his mind's eye a sort-of floor plan.

He's most definitely not alone by the time he comes to the strange device with the cavity and the lever. It seemed obvious to him that something needed to fit in that space and so Sephiroth took a few steps backwards, widening the scope of his vision around the immediate area, particularly looking at the water on the floor itself; there should be an obvious ripple or distortion in the way it flowed even if still, if indeed there might be something just underneath the surface.