In search of a fruitful idea, like the Trinity

In a recent post, I characterized novel ideas as something like fugue subjects, something that can be reversed and transformed and played against itself, in the form of other characters, subplots, locations, etc. If it has that flexibility and extensibility, it can serve as the basis for a novel.

The same is true, I think of a variety of other ideas. Some ideas are fruitful, that is, they lead to other ideas. In another post, I wrote about the writer Ron Carlson's notion that, when writing, you should make sure your narrative choices give you "inventory". You make initial story choices not just on behalf of the plot, but on behalf of the future self that will be writing the rest of the story. You want to keep that person from running out of stuff to use. I've also written about how irritated that person will be if you aren't careful to do that.

In Christian theology, the Trinity plays something of that role (how's that for a dramatic transition?) The Trinity became dominant as a concept, not because it is, in some sense "truer" than, say, Arian monotheism, Monophysite spiritualism, or Nestorian humanism, but because it allowed for an incredibly complex narrative. Someone could always grab some part of that idea and develop an entire theology out of it. As a result, Trinitarian sequels, spin-offs, and fan fiction outcompeted the more closed-off and conclusive narrative notions of other Christological constructs. 

Having explained both post-Nicean theology and novel writing, what can I do next?

I can go in search of a fruitful idea.  I just sent my novel to my workshop, and have new tasks to take on.