He's not quite sure what he's thinking when he does it. He hasn't consulted anyone else on the team, nor SHIELD. Though, by now, SHIELD will know where he is.
He's surprised Coulson's not already been forced through the door to stop him – armed with nothing more than his shades and a disapproving frown that can halt even Tony Stark in his tracks.
But the Tower is missing something, in a space for two assassins, a demi-God, a super enhanced soldier, a billionaire and his girlfriend, and a green rage monster.
Steve isn't quite sure why he decides it's the dog they are missing.
He pities it slightly. It's going to be living in a madhouse.