How do Combat Bystanders behave, and how can you tell them apart?

Question

Accepted Answer

A Combat Bystander carries the combat symbol on its card, which players call a fist icon. In the Enemy Phase it acts like a Trooper, hunting Zombie Heroes with an Attack or a Move, and it does not try to escape. An escorted one with no Guard in its zone does not move, but still attacks a Hero in its zone.

Marvel Zombies: A Zombicide Game

How do Combat Bystanders behave, and how can you tell them apart?