Ed's eyes widen in shock when he sees the darker April, but he doesn't move to attack; at the moment, he can't bring himself to. It's April, but... at the same time, it's not. He has to remind himself that if it comes to violence... this will be like fighting Sloth, the homunculus he and Al created when they tried to bring back their mother. This woman may look like April, but she's not, no more than Sloth was Trisha Elric.