Movie of the day is Boogeyman again. The skeevy man with the loud sound effects from the bus is complaining. People who talk as if trying to start a conversation, but to no one or everyone, are far more unnerving than people who are clearly just externalizing their internal monologue. Depending on the monologue, of course.
Snape is a special fictional situation, as is Draco. They were both written unsympathetically but in a very human fashion. They have lines and blocking, not motivation.
I think the easiest way to explain the appeal of Snape and Draco as characters to re-envision is to first show The Wizard of Oz, then take in Wicked. Like heroism, copyright has an expiration date. What would L. Frank Baum think of Wicked? He's dead, so we won't know until Timeheart.
But the difference between very good fanfic and Serious Literature may only be an accident of timing.