A really random ThunderShield concept I've had in my head for months is 1930s Brooklyn, Steve and Bucky are wandering around a fair when they see a small crowd standing around something. It's a hammer, and they're trying to lift it. The guys are laughing and rolling their sleeves and trying to pick it up but it's too "heavy".
Bucky tries it too, for fun. They're on a fair, right? And it's free so why not! The thing does not budge an inch. Come on! Bucky calls to Steve with a smile on his face, you try!
Steve doesn't really want to try it, knowing that if Bucky and all these strong guys can't lift it, he most certainly can't. With some pushing of Bucky's sisters he walks up the hammer, stands in line for a moment and then grabs the handle. It feels weird. Like tiny zaps going up his arm and he almost releases the hammer in surprise.
Then, he yanks - and the thing flies up like it's made out of paper.
As Steve and everyone around him gapes at what just happened, a tall man pushes forth through the crowd, dressed in silver armor and a cape, and his long blond hair sways along with his large steps.
"Ah, there it is!" He exclaims, when he sees Steve, "I already wondered where she was!"