Starting with smol Sam and human Dean, Dean tends to be grabby but not casual, he’ll pick Sam up but only if it’s necessary. He’s more likely to let Sam get up on his own and tries to give him complete independence. Sam occasionally bosses Dean around, but it’s not often and he mostly leaves Dean to it.
With smol Dean and human Sam, the interactions are much more casual. Sam will poke and nudge, pluck Dean up and plop him on his shoulder. Dean will get used to getting moved around, and scolds Sam if he was busy. Dean will also be extremely bossy, making sure his giant little brother knows just who’s in charge, no matter how often Sam teases him by picking him right up in the middle of a tirade.
They’re an interesting crew, to be sure.