Dean continued packing until Lisa mentioned that she had a question, at which point his attention had shifted fully to her, a bit of a curious lilt in his expression. Though, once she posed it, that curiosity quickly shifted to what looked more like pain, and he followed it up by tearing his attention from her and shuffling through his duffel bag, again.
Dammit. What was he supposed to say? Obviously not the truth, since as Sam pointed out, any information about his past could rip apart the angel wall, and that was a pretty big piece of information. At first, he just sighed, saying her name like he had every intention on lecturing and denying his way out the door, but then he looked back at her and registered the look in her eyes, and he stopped.
"Look, there are some things I haven't told you. About me. About my past. But believe me, it's not as bad as... whatever you're thinking," He said seriously, enunciating with his hands. "We... we used to do a lot of hunting," He offered by way of some explanation, hoping that word didn't ring any bells in the missing sections of her mind as he turned from her again to adhere the sides of zipper on his bag.