Steve nods, slowly. If in seventy years, with samples of his blood, his own government couldn't work out what Erskine had done-

Different world, different rules.

"Once it's done, I'd like it destroyed. Once I'm home. The samples, the notes, everything." He drags in a deep breath and goes back, coffee in hand, to hold the door for her again. "I've seen what Dr. Erskine's work can do. I've seen what abusing it can do. And I won't let that happen, not to y- Your. World."

He takes a too-long drink of coffee and ends up burning and choking himself at once.