What you're seeking for is where you're seeking from.
If you are an atheist, God and Satan are inventions of the same concept, and therefore cannot be apart. Just as two poles of a magnet must belong to the same object, God and Satan are inseparable concepts and forces.
If you are a theist, God created all Beings, to include Satan, and therefore cannot be apart. God, who is all-powerful, could not create a being that could defy Him, even through free will, otherwise God is not omniscient and could not contain free will in the plan of creation.
If you are spiritual, God is another label for The All / Source / Infinity, which includes and is not separate from Satan, which is a label for that which distracts one from the realization of one’s true nature (The All).
If you hold to Gnostic understanding, you will also recognize Jehovah to be a name of one god, which acknowledges through duality another entity, here called Satan. Since they are collaborating over Job in the story, it suggests that they are of the same kind of entity.
Either God’s plan of creation includes free will, otherwise God created robots that are ultimately influenced by Him. In fact, both are true: God created consciousness that is annulled by Him (i.e. ‘robotically’ influenced completely by His ‘light’), with the design that we would take responsibility and evolve to become conscious creators in our own right, independent of God’s influence.
In between every two extremes is a middle that consists of the union of opposites. When we arrive at this center within ourselves, we deepen into something that exists beyond choice.
To choose means that I must move from here, to there, either inwardly, or outwardly. But this movement is an illusion constructed by our sense organs and our perceptions. The notion of choice in itself is an illusion. What motivates one to recognize a set of options is not an independently free action, but rather an influence based on some first conditions causing the desire to choose to arise. However, if we really understood this, we would see it for what it is, which is ultimate freedom, rather than what our mind perceives choicelessness to be, which is the idea of ‘lack of choice’, or slavery.
In actuality, lack of choice and choicelessness are not the same thing; the former implies that a choice could be there, but is not. The latter is an understanding that both or all options of a choice exist, but are no longer distinguished, favored, or judged from a position of mind. They are simply allowed to exist, and no longer dominate the focus or the drives and desires of the individual. Thus, they cease to hold any importance or influence for the individual, and choicelessness is attained.
To the mind, this may sound like the surrendering of our freedom, our free will, our ability to choose. However, there really is nothing to surrender, other than the attachment we have to the choices we’re presented. Instead of championing our ability to choose between what’s presented before us, we arrive at our true nature, which recognizes that choices may or may not be present, but that does not allow such choices to dictate our inner state, causing us to lose ourselves to the choice.
Our choices do not matter; what we choose does not matter. What matters is the level of consciousness we bring into the process of making choices. Instead of placing free will or choice as the highest thing, the awareness of the agent making the choice is recognized to be the fundamental reality.