Julia was kneeling, reaching underneath the kitchen table to collect an errant dog toy when the owner of said toy, Rex—a massive, 105-pound (approx. 48 kg) pure-bred German Shepherd who was still very notably not fixed—decided to mount her. Julia, weighing barely over 100 pounds (approx. 45 kg) herself, could only offer a cry of surprise as the dog's overly amorous advanced knocked her over.
"Rex, get down from her! What's wrong with you?" came a voice from the kitchen. It belonged to Julia's mother, who was striding toward Rex with a stern look on her face and a wagging finger. Rex, respecting her authority, gave Julia a friendly lick on the face before padding off to his bed in the living room. Julia's mother sighed. "You alright, Julia?" she asked.
"I'm fine, mom, thanks," Julia responded, "He just took me by surprise is all."
Her mom shook her head and started walking back into the kitchen. "I don't know why we haven't gotten Rex fixed yet," she called out to someone else in the house. "This keeps happening, and he's not exactly a puppy anymore."
"You know why, honey," a male voice—Julia's father—responded shortly before its owner entered the kitchen. "He's purebred and weighs over a hundred pounds. We would be throwing a fortune away if we got him fixed before breeding him a few times."
"Yes, yes, I know," Julia's mother grumbled. "Still, it's only a matter of time until he accidentally hurts someone, I swear."
"With such an amazing trainer as you working with him? Not a chance," her dad answered his wife with a grin and a kiss. "Speaking of, look at the time. We gotta go, hon."
Julia's mom glanced at the clock on the wall with surprise. "Shoot, you're right. We're going to be late if we don't leave right now." They were supposed to be going to a dog training seminar for owners of purebreds; neither of them had ever been professional breeders or trainers before, but, having reached a certain level of financial security and affluence, Julia's parents seemed determined to give it a try. Julia's mother walked over to Julia, who was climbing to her feet, dog toy in hand, and gave her daughter a kiss on the cheek.
"House is all yours, dear. We'll be back some time this evening. Try not to burn it down while we're gone," her mom said, before heading toward the front door. On her way there, she turned and said, "Leftovers in the fridge if you get hungry, or just order something. Up to you. Okay, bye!"
"Bye, mom! Bye, dad!" Julia called, watching as they both disappeared down the hall to the front door of their house, then listening as they closed and locked the door behind them. A couple minutes later, she heard the engine of the family SUV start up, the garage door open, and then they were gone.
Which left Julia alone with Rex, who by now was passed out on his dog bed. Julia tossed his toy into a basket of other toys and looked the dog over. He was a good family dog, protective but friendly, playful but gentle, and she always felt safe around him. His only real mark against him was his tendency to try and mount other dogs and people around him, and that was a male dog thing in general, not anything really against him in particular. Not to mention that, lately, Julia hadn't minded the attention at all—she was in the grip of puberty, and like all pubescent preteen/teens, she was often incredibly horny. Like right now, for instance. She hadn't been, but Rex attempting to mount her like some bitch in heat and lit a fire inside of her.
She sighed and prepared to venture to her room to spend some time with her vibrator, but then her eyes drifted over Rex's cock (still remarkably pronounced, even while sheathed) pronounced testicles and she hesitated. She knew what she was considering doing was wrong, because animals couldn't consent... but on the other hand, she wasn't so sure that was true. Surely Rex had made his desires perfectly well known just now? Surely there wouldn't be anything wrong with satisfying Rex's needs as well as her own. Surely. And besides, Rex was the family protector, and she knew he wouldn't hurt her, unlike any boys she might be interested in. So... fooling around with Rex couldn't be bad, right? There might have been additional reasonable objections to her desire to engage in bestiality, but with her hormones raging, she had no interest in considering them.
Having decided to fool around with the family dog, Julia now paused, looking over his sleeping form. The question now was, how to begin?