So I wrote a response to this and AmtrakConnect ate it. What the f*ck, man.
Let me try and rewrite it:
I'm going to explain what I meant about showing one's emotions openly. Because you're right, Inukashi didn't have the complete freedom to show his emotions that Shion had. But I think that when he does show an emotion, he does it in much healthier ways than Nezumi and Safu do.
You see, Nezumi is completely repressing his emotions. Whatever he's feeling, he wants to deny it. If he has to express an emotion, it usually comes out as some kind of action, an action which usually brings bodily harm to other people. No matter what the real emotion was in the first place, someone ends up getting stabbed.
Safu, on the other hand, doesn't really use facial expressions when she's expressing herself. I mean, she does, but she relies a lot more on words. Very blunt words, too. To me, it always seemed a bit like she put her scientific side between herself and the world. She doesn't seem very spontaneous.
Inukashi, though. When they're happy, they laugh. (See: Shion getting tricked by their assassin's ring.) When they're in pain, they cry. (See: Inukashi getting their toe sewed up by Shion in the beyond). When they're annoyed by Rikiga, they argue with him. I think that their emotions are very spontaneous and natural, when they choose to express them.
I think you're right and that Safu being direct is a good thing, because it will make Inukashi feel free to express themself all the time, instead of only some of the time. On the other hand, Safu needs to suspend that scientist self that intermediates between her emotions and the world.
Hope that made sense. Also, hope it was accurate, because I can't check the anime until I get off this train!
Oh, and I like your metaphor of the dog that is afraid of being hit... (But a dog would growl, or alternately wag its tail, right? They'd let Safu know they were afraid...)