And today, the funniest of them all was shown: jealousy. When my dad petted the cat, the dog went absolutely nuts. But the cat isn't exactly above that same attitude; if another animal (the dog included) is receiving too much attention, he will rush in and try to get some himself, intensely jealous of the other animal.
It sometimes seems to me like they're almost siblings. (It sort-of fits, even: both were originally the pets of my younger sister, who is currently away at college, thus, both have the same "mother", and we're looking after them as grandparents and aunts.) Heck, there's even a bit of a big-brother, little-brother relationship based on their size. The big brother cat intimidates the little-brother dog, so much so, that it can be hilarious watching how much the dog avoids the cat.
...But when the dog is oblivious to the presence OF the cat (e.g. he's really, really excited), especially if he gains momentum in his movement, the tables turn and the cat is visibly nervous of the dog, even running away. Which reminds me of how--while I always was afraid of my brother--he could occasionally be scared of me when I got really angry.
Animal experts may equate this behavior that I've described differently, but I am of the opinion that animals are a lot like humans. (Well, technically, I'm of the opinion that humans are just animals like any other, but some people take offense to that wording thinking I'm cynically implying barbarism when I'm actually optimistically stating that animals can feel basically everything we can feel; we just don't recognize it.) Thus, even if it may not be technically true, I like the idea.