Ugh. We should have seen more of them talking, not just out loud but also in their head, while someone else was in the room. And I don't mean in the 'There are no other important characters in the room and it's not really important whether they're talking out loud or not' way.
More of the 'He's not listening' type. Just. Adam telling the Winchesters what Michael is saying (aka yelling in their mind) while Adam is fronting and then after a minute being frustrated and going 'You know what? I am NOT playing angel telephone'. Michael fronting and Adam is talking to him at the same time as the Winchesters, commenting how annoying and full of themselves they are. (And reminiscing about how he never got to eat that piece of cake.)
At another point, Michael just 'listening' to the Winchesters with a blank expression for a minute and then going 'Oh were you talking? I was listening to Adam.' and Adam's projection going 'No, you weren't' (but ofc the Winchesters can't hear him so they believe Michael).
Adam saying something and Sam and Dean are confused, but 'Oh I was talking to Michael, don't worry about it. Yeah, he's being kind of annoying right now, no, shut up, I told you we're not gonna smite them!'
I just. Have a mighty need.