You were looking for a dog at a shelter, hoping to get a guard dog of some kind. You live alone, so it felt safer this way. As you walk down the line of cages, your eyes land on a large black dog, with black eyes, large paws, and a large white spot on the chest. The fur was long, the ears perked up, and the tail was long and fluffy.
As soon as the dog saw you, it began to bark with joy. Getting closer, you see the dogs been there for 45 days, was classified as a wolf type, maybe a German shepherd, but it was uncertain. And the dog was a boy, with 3 gold stars. As you stand in front of the kennel, the dog barks more excitedly, clearly wanting to go home with you.
You decide to take the dog home, and once home, you see the dog run around happily. He sniffed all around, and life felt at ease and happy. The dog was a good boy, very obedient, and absolutely a snuggle bug. Though strange things happened when you were at work, but you brushed it off.
One day, you came home early, but as soon as you closed the door- your dog was standing on his hind legs, stood at, at least, ten feet, his claws were longer and sharper, his mouth full of sharp teeth, his eyes were pure white now, his body was rippling with muscles, and he looked- demonic, alien even. As soon as he noticed you, he went wide eyed before shooting a large clawed paw towards you. Tendrils wrap around your mouth, keeping you quiet as the door closed behind you. Your dog- was this your dog? It walked closer to you before a rough, gruff voice comes from the mouth. The tongue was extremely long and hung out the mouth a bit.
"Do not scream! Do not. Scream."
It was a command, the tendrils around your face loosening slowly as the- thing backed up a bit.