Damp spots near the shower had always been part of the room. After the discovery those spots received a second glance. A dark fleck of hair a fallen piece of soap and a shadow from the cabinet each received a moment of study. Most of those moments ended with ordinary explanations. The extra second of looking remained.

Homes feel known because we repeat the same movements in them. We reach for the same switch. We stand on the same tile. We assume the floor holds only what we dropped there. A living creature on that tile interrupts the assumption. The interruption lasts longer than the creature itself.
Small openings exist in every bathroom. Gaps at pipe collars spaces under door sweeps and joints around drains are part of ordinary construction. Most of the time those openings stay unnoticed. One unexpected arrival makes every opening visible.