Who’s more like a cat, and who’s more like a dog?
I think Kakashi is more like a cat. He has that quieter personality, and I see him as the type who won’t directly ask for attention when he wants it – he just so happens to be in the same room as Iruka, and just happens to be using his legs as a cushion while he’s spread across the lounge; meanwhile, we all know he wants company and cuddles. Also, cats can be a-holes sometimes, and I think it’s safe to say that Kakashi reflects that attitude as well, especially when he’s always teasing Iruka just for the hell of it 
As for Iruka, I think he’s more like a dog. His emotions are easy to read, and it’s very easy for Kakashi to tell what he wants; and when it comes to affection, he won’t be subtle about it. Dogs can also be quite vocal, and we all know Iruka isn’t afraid to speak his mind! Especially if it’s to protect someone else. He shows his love outwardly rather than internally; and when he is around, Kakashi is always reminded just how much he cares for him 
Those two are opposites, but they complement each other so well 
What do you think?