This couple adopted a new pet, an adorable corgi from a shelter. They were warned that this corgi had quite a few former owners, all of them going missing with just corgis found in the house.
Everything seemed to go alright, except he was a very disobedient dog. Eating their food, sitting on their furniture, acting like he was in charge.
Finally one day they came down to the living room to find their corgi wearing a mysterious crown, sitting on the couch with a very human grin.
"Looks like you both need to see who is in charge here", the corgi said. They found themselves growing dizzy, and falling to all fours. Their tongues lolling out, and their clothes falling off as they shrank. Walking forward on changing paws, to nuzzle against their ruler and master.
More corgis for the corgi army. Soon Corgi King would have enough to begin his plan to conquer earth and make everyone worship and obey him as corgi servants.