There is something magical about the relationship between pets and teens. They seem to love one another unconditionally, and pets seem to bring out the best in teens.
No matter how cranky a teen might feel, it is unlikely to manifest itself at the family dog or cat. No matter how frustrated a parent might feel, seeing their child curled up with their dog or cat is bound to pull at the heartstrings, and watching an animal say hello to a child who has been gone for an hour, a day, a week, or longer, is truly joyous.
When we consider adding a pet to the family, most parents initiate a conversation about responsibility and extract some (highly unlikely) promise from the kids that they will feed, water, bathe, pick up the poop and walk the beasts, but maybe the more relevant conversation is to make a promise to love the animal.
I propose another perspective on pets - they are like an emotional safety net for teens. When a teen is not sure they like anyone in the family, at least the family pet is there to keep them company and remind them they are loved!