So I'll try to invite a conversation (if only this topic could attract as many readers as a post on Chick-fil-a). Earlier today I posted this status update on Facebook,
The Spirit is being-as-possibility in its non-subsistent isomorphic ipseity. Precisely in this way is the Father freed to be the Father, the Son to be the Son, and all three themselves in their mutually coinhering circulation around the neighborhood.
Typically in Western theology, the Spirit ends up being the shared love of the Father and the Son. So the Father and the Son are "subsistent" beings, clearly identifiable as persons because of their antecedent narratives, where as the Spirit is the love between them.
This is helpful as far as it goes, but it risks leaving little "there" there for who the Spirit actually is as a full person in the life of the Trinity.
The question is, "Where does the Spirit 'stand' to be him or herself over against the Father and the Son?" One of the best, but in my estimation, still insufficient responses, is that the Spirit is God's own liberative future.
In the East, on the other hand, the Spirit is really more independent as a person (no filioque, for example), but then all the processional and monarchical language of that tradition ends up making all three members of the Trinity more static even than in the West, since the Spirit is in a sense less free to set the other two members of the Trinity free in their particularity because the ontology in the east is more being as persistence rather than being as possibility.
Theologians wrestling with this have thus tried to find a way to speak of the Spirit as God's divine future, thus grounding the Spirit not in a developmental past but an anticipated future. And the "isomorphic" aspect of the Spirit is that it puts the "is" back in "is."
How do you in your own reflections wrestle with this?