Just came back to re-read this, and I love it. Also, I like the point you make here: Bruce really would admire Clark's self-control, and Clark is more constantly controlled than even Bruce is, so that's one more thing they have in common, when often they're portrayed (in the comics) as being so different as to be almost opposites.

tiny nit-pick: you wrote "Bruce felt familiar lust and wonder grip him at the power leashed in his lover, the raw strength reigned in and turned to tenderness." I think maybe that should be the horse-riding term, "reined in"?