I would be interested, but it does seem that Jareth has been the pivotal figure for the vast majority of the time, so I would like to see someone else come to the forefront. While I'm here and while secondary characters (those who aren't in the main quartet) are in question I'll also mention that it would be very nice to see Eponine come into her own and not just be the chick in the 'minimalist' clothing who keeps pouncing on Jamie.
I wanted a vote about halfway between Intriguing storyline, and inscrutibility suits. Mebbe would be working better if you interspersed it between other chapters of the arc(s) in question. Would be like short breaks with LKFs (little known facts) about him. Love your portrayal of Erlkonig, and while I want desperately to know his motives, I like the idea that as a Fae, he is verra inscrutable
I'm always intrigued by the motives and back stories of the characters. The more we know about them, the more relatable and likeable (or at least understandable) they become. I'd love to see more of him.
Mysterious is a good thing, but it can only go so far. The Erlkonig is very attractive (as a character!) when his motivations are unknown, but if he remains that way, I will eventually get bored of him. That's why Steven Moffat isn't my favorite Who writer. I hate the way he keeps the fandom in the dark and tries to mislead them all the time. I mean no offense to anyone who does like Mr. Moffat's writing style. In conclusion (didn't mean to write an essay, but there you go) I think it's a good idea to tell us a bit more about the Erlkonig.