I don't know which enemy you are talking about. The enemy from vent comes out of the toilet when you enter the bathroom after the vent opens and you do not close it. The same enemy will appear randomly in the house if you do not close the ventilation. There is also a painting in the attic - if you don't collect the cross lying next to it, the angel in the painting will kill you later in the game. This is Point & Click game, but the environment is in 3D. Only lamb and enemies are 2D objects.