The optics of a Decepticon are red, they all started out 'good', with blue eyes. Then when Megatron turned against his brothers (or however the story goes), did his optics just turn red? A flick of a switch on their back? They inject themselves with something to change optic color? I realize I'm probably over thinking this, and when it comes to Transformers, well you shouldn't do that, but I'm just curious to see others thoughts, to see what theories you have, and what you think.