When I see this part in the movie I think to myself "The face you make when others are fighting and you're awkwardly witnessing it." <-- Or being on their side till it gets too intense or I see no way out. Then I suddenly have nothing to do with it.
Story of a Five Year Old Avenger, Meeting The Avengers "Chris Hemsworth is walking away, so my son shouts out, “Thor!” Thor turns around, smiles and waves, then continues on his way. But there is Loki, the God of Mischief. He sees my son, and smiles.