Kate vaguely remembered hearing about that. "But didn't the Argents kill Derek's whole family?" she asked. She might not be close to this particular Derek, but she had been good friends with several previous iterations and one of them had mentioned the fire at some point.
Of course, if she remembered right, Derek's mom died in that fire, so she was pretty much hooking up with one of the people responsible for her death. This was definitely the kind of thing that only happened in Madison Valley.