Ruby was both mildly impressed and slightly disturbed at the sight of the bone pile. Whomever could make this was obviously a killing machine. Then again, he/she was a killing machine, and Ruby was in its lair. Lacking any heat signature, Ruby began a scan of the area, hoping to get a concrete view of the structure of the cave. While the eyepiece's scanning range didn't reach to the very back of the cave, it did reach to the bone pile. What she saw gave her pause, at least for a second. 

With bones strewn about it, some... horrid... thing, with the wings of a bat, lay almost completely still. Memorizing the layout and position of the bones, she unsheathed her knives, and held them in both hands, creeping up on the.. thing, silently, and avoiding the bones, so almost no noise was made, except her soft, controlled breathing, and her mildly increased heart rate.