See Tim Harris here as he explains with real clarity the relationship within the trinity and its implications.
We can note that there is not reciprocal identity—they are distinct and not to be confused. And without making the error of suggesting that there was a time when the Son did not exist, we also observe the Father is the kephale – source of the Son, and the Son is ‘begotten’ of the Father, while the Spirit ‘proceeds’ from the Father. This much is not the point of this post, but the backdrop to what follows.
While the hot issue is whether the Son’s submission is eternal (and if so, whether this is functional or ontological), I wonder whether the wrong question is being explored. It is less the timeframe of such submission, but how that ‘submission’ is understood. Is it necessarily a hierarchical notion, of command and submission?
H/t Peter Carrell