User blog comment:FTWinchester/Holy Terror/@comment-11331875-20131204113750/@comment-174.49.83.252-20131205224508

I figured the reason Anna exploded and Castiel didn't is because of bloodlines. When Anna removed her grace she planted herself in some lady's womb. I don't think she was paying much attention to whether or not that bloodline could contain an angel. On the other hand we know that Castiel's body AKA Jimmy Novak can contain an angel.