pruning again

The pear tree is in blossom outside my window. The blossoms come before the leaves. Last weekend I was two steps up on the small stepladder, trying to clip the watershoots on the Transparent tree before they bloomed. I put some of the clippings in vases (well, in pitchers, we have no vases) for the contrast between the smooth cupped petals and the rough twisted twigs. Finally hacked back the lilac beside the house, and took some cuttings to watch the tight green leaves open on narrow elegant stems.
If only revising were as clean to do. I trim out characters and scenes in the modern-day storyline, with a vague hope that I may use them elsewhere--drop them into other storylines and see them open up--but then must continue through that scene and the next, making sure no trace remains to jar the reader. More like uprooting blackberries or holly, that send shoots underground to pop up annoyingly in a space you thought was clear. Or, I suppose, more like weeding than pruning, done on your knees, laboriously with eyes to the ground.
What I need to learn is how to keep background characters in the background. I want more than the principal characters to be visible, because I dislike stories where no one seems to be in the room or the building than the two main characters (I keep wondering what passersby or the cleaners or the busboy think of their conversation or their goings-on.) I want passersby or cleaners or busboys, or the guy in the next cubicle, so the story feels more real, or more thoroughly imagined.
But when I write background characters, they move into the middle ground, where they draw too much attention. I don't know whether it's the dread 'hey, I'd rather read about this guy than your boring protagonist', but it's something I need to work on, as I engage in the selective erasing of characters.