The certainty that it is not a joke drops onto him like a block of ice, because there's no way that Steve would hear that waver in his voice and keep up with the joke, especially not with that serious an expression, not with the way he was cataloguing everything around him - Dick recognised that look, he was watching out for a weapon if necessary.

"Steve... I don't..." he was lost for a moment, uncertain, but he found his feet again and tried to explain "My name is Dick Grayson, I'm your friend, you let me stay here... you really don't remember me at all?"