She should have heard him. Probably would have if she hadn't been too focused on putting one foot in front of the other. But when she heard Zacks voice call out to 'Sephiroth', she froze.

Fight or flight.

On a normal day she would have stood her ground. But right there and then she wanted to run. She could have ran if she wanted, and run fast! Zack wouldn't be able to catch up in a million years.

And yet... she was frozen to the spot, struggling to work out what to do that wouldn't rise more suspicion. In the end she chose to force her feet back into movement, just walking, back straight though her head lowered enough that the hood of the cloak kept her face in shadow. There was no reply to Zack. Why would there be? She was supposed to be Sephiroth, right? She could probably get away with just a raised eyebrow or two and a hum here and there to carry the conversation, she wouldn't even need to open her mouth! Though she really really hoped Zack would get bored and just carry on his way...

Though Aerith knew her luck wasn't going to be that good.