At the end of the day it was just another vampire, but it wasn't that simple was it? She had let the thing bit her, for whatever reason, turn human, and then she gutted it. It would have been so simple for her to kill the vampire when it was still a vampire, and simpler still for her to kill a human quickly. She was skilled enough to kill a vampire before it could get her or Dean would never have let her patrol, so why had she made decision after decision that was so unclaire?
It was such a shapr shift that Dean was convinced it had to be one of two recent changes--the future people showing up, or Sylar. Dean knew that everyone from blonde Claire to Natalie was effected by the unwanted arrival, but Claire seemed to be taking it much differently than her sister.
He recognized that look from the time he had been lost between getting his memories of hell back and starting slowly on the road to recovery. She had helped him with that as his best friend when his life was falling apart and he didn't know how he'd make it through another hour, let alone another day, and now he'd help her through this. She had gutted a human, but a vamp turned human wasn't really the same thing anymore. Besides, what was one half human thing compared to the atrocities he had commited in hell?
She was broken, Dean could clearly see that, but he had been broken before too. Sometimes he still was. She was his Supergirl when he needed her, the one at his side helping him heal, and now he'd do the same for her.
"It was a vampire, Claire. Turning human again briefly doesn't change the fact it wasn't human anymore. Whatever it was it's over now." He leaned in again, trying to kiss her, to hold her, to help her the only way he knew how.