Captain America (Movies) The Avengers (Marvel Movies) - tolieawake

Steve Rogers has a tendency to leave his left side inexplicably open, and no-one, from SHIELD scientists to Natasha can figure out why. And then they can.

On his left

It doesn't come up straight away. When Steve is first defrosted, they're too busy checking his general health and reflexes and trying to gently ease him into the new century to notice.

Natasha is the first to notice, during those nightmarish hours that later become known as the Battle of New York.

"You drop your left," she tells Steve.

In the midst of wrapping his hands for yet another go at Tony's latest attempt at an indestructible punching bag, Steve pauses.

"Thanks," he says, "I'll try to stop."

Natasha frowns, because that isn't exactly a guarantee, and then spends parts of her free time sparing with him until it's less noticeable (he never quite stops dropping his guard there).

-

Sam notices it next. In the way Natasha tends to stand on Steve's left. The way Steve will always put others on his right. Even the short conversation with Natasha where she warns him to watch Steve's left - because he keeps dropping it.

Sam doesn't know then, but while it's less noticeable than it was, - Steve working hard, when he can bare to - it's still there.

Interestingly enough, the Winter Soldier always attacks Steve from the right.

Sam doesn't know if he noticed Steve's tendency and in some weird way wants a fair fight or something, but he's glad, because he's pretty sure that if the Winter Soldier attacked Steve from the left, Steve would lose.

Sam being Sam, once Steve no longer looks like death warmed up, he brings it up.

"You drop your left," he says.

Steve grimaces. "I know."

"Wanna tell me why."

"Not really."

"Are you gonna be able to stop?"

Steve shrugs.

"Okay then."

So Sam spends a lot of time guarding Steve's left.

-

It's only when they're back in New York, Steve's best friend, ex-brainwashed-assassin in tow, that Sam thinks he begins to realize why Steve always drops his left.

Natasha takes one look at them, goes "huh" then promptly tells the best friend, ex-brainwashed-assassin something in Russian. He frowns at Steve and nods.

"You gotta stop dropping your left," Bucky tells Steve.