The song itself is humorous, isn't it, despite the ending--I think that's why I knew the story had to hae a light touch, despite Snape being initially unwilling to sit down and talk.
I love your concept of it being Harry's own subconscious wranglings! In a way, I think that's how the writing process for a "talky" story like this can be said to work. I start out thinking, how can I get a reluctant Snape to give a pursuing Harry just enough info to come to understand what was going on between the two of them? And the conversations just arise from everything one person says and what the other person says in response to that, and on, and on, and on. Except it's really in just one person's--the author's--head.
And I'm so glad you liked Snape! He always gets the best lines. ^_^