I've been wondering about that dog that appears in two missions and guides Franklin to people that need help.
With Franklin talking to it, I've heard theories it is a spirit or part of his consciousness. But I'm wondering if there is more to it than that.
The thing is, I think I came across this dog again outside of the missions. It was a beach area, there was nobody around, and the dog ran up to me and started barking. Then, it went into the sit position and just sat there for ages. I thought this was unusual since unlike with Michael or Trevor, dogs tend to attack Franklin. But this one looked the same as the mystery dog, and did not. It just sat there for ages, until I shot a guy on a jet ski a few minutes later, and then it ran away.
I haven't heard of anybody seeing the dog outside of missions, so just thought I would throw this out there...