There have been a few threads on the subject of the ‘Holy Guardian Angel’ today, so I figured I’d drop my two shillings into the pot.
The HGA, isn’t holy, a guardian, or an angel. It is your perfected self, the ultimate amalgam of all your selves united and reconciled as one.
The lighter self is the most ‘light’ or selfless version of yourself, which from your perception of ‘moral good’ is derived.
The darker self is the most ‘dark’ or selfish version of yourself, which from your perception of ‘moral evil’ is derived.
What I propose is simple, your darker self is inherently that which you would become if you absolutely abandoned what morals you may follow, and your lighter self is what you would become if you followed your morals to their logical end. The perfected self is what happens when you reconcile both your lighter and darker selves within yourself in a way that is non-contradictory. Seeing how the lighter and darker selves by their nature are opposites, and thus contradict each other completely, you can see why you may never become your perfected self.
The beauty of this is that you have the free will to choose your own path, for your own personal light or dark, or even tread the middle. Heck, if you wanted to, you could reject both your lighter and darker selves and change utterly on the most basic level, although that way is what I would consider madness.
And as Crowley said, Do what thou wilt shall be the whole of the law, so ultimately, what you do with what I propose is up to you.