"When you look at Elena, do you ever see Katerina?" The question strikes Stefan as odd—mainly because it is asked as they're feeding on a pretty redhead who won't stop whimpering. (Stefan hates the noise, but Klaus insists on dragging it out.)
"Do you?" Stefan wants so badly to ask in reply. He is not suicidal today, however; so instead says, "I'm not sure."
Klaus drops the girl without preamble. Her eyes widen and she makes to scream, but her head hits the pavement and the only sound is the crack of bone. "Wrong answer."
"The question was simple," Klaus reprimands as he turns away. "Do you ever see Katerina when you look at Elena?"
-x-
If it were Katherine that was asking, the answer would be an automatic 'no.' Stefan knows this almost immediately, because no matter the truth, he knows never encourage an ex-girlfriend when she is trying to kill the current girlfriend.
If it were Damon that asked, Stefan wouldn't even bother with a reply. Damon's goal in life is to undermine his relationship with Elena in every possible way. Katherine and Elena being identical is just an easy thing to exploit.
If Elena were to ask, he would tell her that in the beginning, he sometimes saw Katherine. Then he'd carry on by telling her that he loves her and that what he had with Katherine was never real.
-x-
The thing is, it is not Katherine or Damon or Elena asking. It's Klaus. And should he tell him? Stefan catches on rather quickly to the test. This isn't about Katherine—it's not even about Elena. This is about truth.
He ponders briefly to himself as he takes care of the body. When he looks at Elena, does he ever see Katherine?
"No," he answers at long last. "I don't see Katherine; but sometimes…sometimes I see what Katherine could have been. What I could have been. What my future could have been, had I remained human."
Klaus doesn't look at him, but Stefan can almost sense the grin on his face for a game well played.