He would never make fun, he's just... not always the best at expressing emotion or reacting correctly. He's intensely glad that Misa seems to be able to pick up on that, and her kindness and understanding are yet another relief, even if he does end up looking rather pitiful.

The kiss comes out of nowhere, and he stiffens, hugging his knees tightly to his chest. The simple, harmless gesture isn't the sole reason, though; it's the fact that it was a veritable floodgate to possibly the largest single chunk of information he's gotten about his past life. Voices, hints, insight... and most of it is fairly chilling. His hand flies to his cheek, but his face is frozen, confused and horrified.

His doppelganger is similarly stricken, more by the volume of information than by the content of the memory.