How anyone can see Death Note as anything other than a tale of absolute power corrupting absolutely is beyond me.
Light is not and never was the good guy.
One could argue that Light was a good guy before the initial L broadcast. In fact, there is an intentionally placed moment in the broadcast where you can see the instant that Light goes from willing to sacrifice his morals because he believes it will improve the world to deciding that questioning his morals is justification to be killed on its own.
Though with how quickly this occurs and with such minor pressing from L, it's pretty apparent that this would have happened no matter what. Whether that means Light was "never good" or just that he was destined to fall quick is up to the viewer.
The moment Light killed that one officer and his ex was the moment that decided where the rest of the series was going to go and I was right every step of the way that he would use everyone around him, even his own family, to get what he wants. The singular moment was what put Light onto the path of corruption. ---
Who knew bananas could be so lethal? Proud member of The Church of The Man-Emperor of Mankind.