Word on the street is that "Captain America: The First Avenger" will have a big role for Cap's WWII allies, the Invaders.
In the 1970s, Marvel writer and Golden Age fanboy supreme Roy Thomas decided to pull a major retcon and say that Cap, Namor, and the android Human Torch (along with various sidekicks and later additions) had been a team in WWII. But if you're reading Nerd Lunch, you probably knew that.
But you just can't use the classic Invaders. Bucky is fine, and even necessary, and is a confirmed cast member. But the Torch? Aside from the fact that Chris Evans already played a different Torch in a couple of movies, Torch is problematic because he requires some explaining. We've been following Cap up until this point in the movie --- regular guy, super-solider serum, etc. --- and then all of a sudden there's an android, so perfect he can pass for human, and he can fly and shoot fireballs?
And Namor is even tougher. He's flying underwater Spock in a green swimsuit, with wings on his feet. You can't just drop this guy into the middle of this movie without radically shifting the tone of the piece.
So I figure, let's use characters that fit in better, that make the cast more international (gotta sell this movie overseas), and/or that open the way to spinoffs. Union Jack (the Brit Cap), his sister Spitfire (speedster, but more like 70 MPH than the Flash), the Mighty Destroyer (sort of a behind-enemy-lines proto-Punisher) . . . and Batroc the Leaper, master of savate. In the comics, he's a contemporary character, and a baddie, but having a savate guy running around kicking Nazis in the head needs to happen.