Close contact with a dark roundish triangular object

11year old on back deck, snow and purple sky, he notices a large object hovering over him (the size of a room) and it was spinning (following his movements). Parent came out to see and it shrunk in size, according to child. Adult and child saw it move directly above about 100 feet up and darted by 100 feet to the left (west) and hovered. Went in house immediately. Child looked out periodically to see object. 1rst check...He spotted it at the end of the yard, North to the tree line, 2nd check seen back near the deck with a long slender human black silhouette on top of a round black disk. 3rd look and moved from deck to tree line, again shape shifting on the way, into a dragon like form that dissipated. Police called to investigate, no footsteps or evidence of anyone or anything around. Dog did not react, in house.
NO SOUND, BLACK as a black hole