It's on the tip of Kate's tongue to say something along the lines of 'see? such a softie' but then Yelena's next statement makes her rethink it. Speaking of challenges... "Absolutely possessive, huh? Prove it."

And then speaking of that (surprisingly unintentional) challenge, Kate shifts just enough so Yelena can see the grin on her face and the glint in her eye, careful to not put any more distance between them than absolutely necessary. "Oh, I'm very sure. Bring it on."