When I am distributing bones to chew on, Dex's concern is that each dog get one. Her brother Fredo, meanwhile, muscles Dex off her bone and munches it while lying on his own, saving it for later.
When I'm sad, Dex empathetically places her chin on my thigh. She doesn't whine or nudge for petting. She just wants to let me know she's there. Her brother Fredo, on the other hand, drops his bone on my bare foot. I'll give you something to cry about, bitch, he seems to say. Not thinking about Roger Ebert anymore, are you?
When I put them outside in the morning, Dex searches for an acceptable place to urinate. It must meet some minimum standards. It must be comfortable. It must be hygienic. It must be private. The process is a huge production. Her brother Fredo, meanwhile, whizzes wherever and is back inside munching on Dex's bone within two seconds.
When I'm angry at Fredo, Dex assumes that I'm really angry at her. After all, I wouldn't be angry if she were making me happy. It ruins her entire day. When I'm angry at Fredo, Fredo doesn't notice and blithely goes about his day, oblivious.