"still could" vs "could still"

Question

I am reading a novel and a sentence kind of popped out at me, so of course, the first thing I thought of was to come here and ask...

What I would say out loud, and most likely write, if I were writing a story: "He could still feel a permanent emptiness..."

What the authors of the novel wrote: "He still could feel a permanent emptiness..."

1. What is the difference in the structures of the two sentence fragments?
2. What would be, or should be, the difference in interpreted meaning, as long as the sentence structures are both valid?

I would point out that both of the authors of the novel are well established and are known, I believe, for choosing their structures with care.

Answer 1

A slight nuance in meaning

"He could still feel…"
He is in the process of self-discovery. He's becoming aware of this recent feeling because it won't go away.

"He still could feel…"
He has known for some time now. Still takes a leading position in the sentence. Emphasis in not on the feeling, but the fact that it has not gone away.

Rhythmic structure changes the tone

There is a steady rhythm in the final version, like a slow drumbeat that feels important, even a little ominous:
He still – could feel – a permanent – emptiness

As opposed to a natural, melodic flow which feels stream-of-conscience and has no clear word emphasis.

my interpretation, emphasizing 'emptiness':
He could still feel a permanent – emptiness
He is attempting to give a name to this feeling.

or emphasizing 'permanent':
He could still feel a – permanent – emptiness
'still' and 'permanent' are redundant, doubling-down on this aspect. It's normal to grieve but his grief has become chronic.

How to choose

The 'spoken' version feels like a discovery, the beginning of a soliloquy about his feelings.

The 'written' version feels like a conclusion. The permanence of his grief is a fact, it's not going away. Everything moving forward must contend with this handicap.