Thanks to the internet, I've seen so many cute photos of people's cats cuddled up together or someone's kitten curled up on their sleeping dog. My pets have never really done this. (Although my cat did used to sleep on top of the hamster cage, I wasn't sure his motives were entirely pure...)
When I've had two cats, they would happily chill in the same room or have a mad scamper after breakfast, but never outright cuddles. And although I've usually found that at least one cat will accompany the dog on his walks and they rub up against each him in greeting, they don't lie down together.
Does anyone have pets who are "besties"? How did it happen?