Re: flyback
During the switch on time you will see a voltage at the secondary windings, which will be simply the input voltage times the turns ratio, but the polarity will be reversed compared to that during the off time.
This happens because transormer action exists always, you cannot cancel it. The same applies during the off time: the voltage you see across the secondary winding will be reflected to the promary with the reverse of the turns ratio and will appear on the transistor' s collector/ drain as a pulse higher than the input voltage.