If you fire an employee out of nowhere, then don't expect them to do you a favor. They don't owe the company ANYTHING!

If you got fired out of nowhere, and a couple of days later you were asked to help out the company by doing something only you know how. How would you react? I would ask if that task would be completed by me as an assistant or consultant and how much the pay would be. I don't think that even when a company mistreated and didn't care for you. I do believe that work connections can get you really far and that a cordial relationship with everyone who has employed you or been a coworker is not only useful but also preferred. Is important to be nice and take some advantage of the fact that you connect with people in your field.