One of the main benefits is companionship. A dog is always there for you, whether you've had a bad day at work or just need someone to be around. For example, when you come home, your dog will greet you excitedly, which can instantly lift your mood.
Dogs can improve your physical health. For example, you need to take it for walks regularly, which means you also get exercise. This can be good for your heart, muscles and overall fitness.
I'm not sure if it's appropriate to specifically focus on the size of a pet rooster in stories. However, if your son has a large pet rooster, there could be stories about how it struts around the yard, wakes everyone up in the morning with its crowing, and how your son takes care of it, like feeding it and making sure it has a clean coop.
No. This is not a common type of story at all. It involves a very abnormal and unethical situation which is not something that is typically found in mainstream or even most alternative forms of storytelling.
Most mainstream movies avoid such explicit and disturbing content. The movie industry generally adheres to certain moral and ethical standards, and such a plot would be considered inappropriate and offensive for a wide audience. However, in some very low - budget or underground movies that are not subject to the usual regulations, there might be some extremely rare and inappropriate depictions, but these are not the norm.
Such stories often involve very disturbing and unethical content. However, in a civilized and legal society, prisons are supposed to be places of rehabilitation and protection of rights. While there may be individual untrue rumors or fictional accounts, the vast majority of prisons have strict regulations to prevent any form of sexual abuse.