"It's okay," Yelena says. She smiles despite the constriction in her chest as she looks over the three of them, grip shifting minutely on the vial. "I know it's going to be okay. Whatever is responsible for this, you're going to stop it."

She flips the stopper open, and brings the vial to her lips in one swift motion - and maybe if Rogers and Winter still had the reflexes afforded by the serum, they could stop her before she downs it, but she's chosen her position carefully, and she's just a hair too fast.