So does your bringing Arianism into the discussion, but no matter. I do not offer this in criticism but by way of observation. 
     I am suggesting that in departing from the first seven Ecumenical councils the Church opened to way for spiritual exploration and ultimately Vatican II and spiritual renewal-but along the way adopted innovations that departed even further from tradition and led to the Reformation. 
    A discussion of relations within the Trinity is hypothetical, while I can tell you something of the Holy Spirit's relationship with me. So can many others. I can theorize reasonably about how the Trinity relates each to its other's member, but with no certainty except to say that the relationship is based on a love we grasp in part just as we know in part and see through a glass darkly. Then, we will know as we are known. (St. Paul.) 
    We can renew our minds in Christ (St. Paul again) or we can ossify in our stodgy theological dungeons.Grow or die. JOIN THE DANCE!