We think we know what's up with Roger.
We were watching "Cats 101" on Animal Planet (yes, I have no life) and they were talking about a rare breed of cat called a Turkish Van. It caught our attention because Roger has unusual markings that kind of match to these cats. Plus, her personality fits (that of a "dog dressed in a cat's body" -- that explains her propensity towards playing fetch).
At the end of the segment, they mentioned that these cats are not good around little kids because they're hunters and they will "stalk" small children. Sorry, Alice-Grace, welcome to the bottom of the food chain.
The good news is that she can't be a purebred Turkish Van. The bad news is that we think she's also part Satan.