For some reason, I can't reply to your response below. But it is not comparable to Lenore in Bloodlust because Lenore had not killed anyone in the recent past. She admitted that she had resisted human blood for quite a while (years?). She was tested and Dean saw that she was able to resist her nature. He evaluated the…

"Big brother is Samurai Cowboy Hunter, little brother is easily misled pointdexter fuckup. Little brother makes mess, big brother cleans it up."

"That Sam let go of the girl adds to Dean's worry that his brother is more than just a hunter."

"It's because Dean's code is the complete disregard of moral grey areas. Since the world is full of moral grey areas, that kind of thinking will never make any fucking sense. Remember the end of season 6? Seriously Dean she killed her own mother to saw your brother. Could you cut the woman some slack? Like no innocent…

First of all, it wasn't a woman. Amy was a monster and her offspring is a monster. Dean is a hunter. His job is to kill monsters that harm/kill humans. He did his job. This is not at all comparable to the situation with Lenore in the early seasons.