This kindled my interest in how the ECF explained John 1:1.
Here is one:
Irenaeus: Against Heresies Book I
Having first of all distinguished these three — God, the Beginning, and the Word — he again unites them, that he may exhibit the production of each of them, that is, of the Son and of the Word, and may at the same time show their union with one another, and with the Father. For ‘the beginning’ is in the Father, and of the Father, while ‘the Word’ is in the beginning, and of the beginning. Very properly, then, did he say, ‘In the beginning was the Word,’ for He was in the Son; ‘and the Word was with God,’ for He was the beginning; ‘and the Word was God,’ of course, for that which is begotten of God is God.”
Of course a Trinitarian rendered this into English...
Yeah, got to check the original Greek. Even so it doesn't sound too consistent with the developed Trinitarian Creed.