He probably shouldn't have put himself between the blonde nutjob and the little girl, if only because Carol wasn't interested in the little girl. She was, however, interested in Ran. Carol had decided a long while ago that she wanted Ran's head on a plate for his involvement with Sarena, just like she wanted Remy's. Truthfully, she wanted Remy's so much more that she almost turned and went looking for him specifically. However, Ran was there, easy, close and accessible.
She could finish him off first. Karl was draining away a bit of her at a time, not fast enough to cause any major slow down, not yet. He was going to need a lot more time before what he did became truly noticable, assuming that she didn't realize what he was doing and rip him into tiny bits before hand. Maybe it was a good thing that she was crazy with a one tracked mind at the moment. She wasn't really considering her opponents, just trying to get at one of the people that she considered to be responsible for destroying the one thing that might have been good in her life.
Carol went at Ran, springing forward almost like a cat would to cover the distance, her fist balled up to try and take off his head.