Natasha's brow arches, and the smile that curls her lips is more than a little mischievous. "She's who I meant when I said the Bartons aren't who you have to worry about."

Truth be told, Yelena might just show up in his apartment out of sheer curiosity. Younger sister pestering takes on a whole new dimension when said sister is also a prolific spy and assassin. "Good news is that I usually get a heads up when she comes to New York."