Phantasm: Dog: Go along with it and get adopted.
From Create Your Own Story
You're taken home by the family, who you find out later are the Hill family. They put you in the back seat with their kids, who pet you on the drive back to their home in Santa Cruz. The boy's name is Tom(21), the girl is Joanne (18), the mother is April(36), and the father is Bill(50). The children are very happy to have you, and snuggle up with you the whole way there.
When you arrive at their home, you find that it's a very nice pseudo-mansion in the mountains. It has a huge frontyard and backyard, a pool, plenty of rooms, and everything a dog could want. You settle into your new life, deciding to wait a bit before causing any mayhem.
Weeks, months pass by and you find that the family is exceedingly nice to you. You find yourself enjoying long nights on the couch, watching movies with the family, sleeping in each of the family member's beds, and living the luxurious life of a well-cared for pet. April enjoys having you run next to her on her treadmill, Bill likes to take long walks and hikes with you, Tom has you sleep in his bed next to him while he plays video games, and Joanne is the most loving of all and likes you to be with her for everything she does. She takes you to school, walks you, plays with you, and lets you sleep next to her.
It would seem she also sees you in another light as well, given the generous number of times you've seen her staring at your large dog cock while she bites her lip. Perhaps now is a good time to act?