Worse than Voldemort/Umbridge/Lucius getting hit by a Anti-Evil Spell and becoming good just because?

 

I think you're a bit too focused on Elise. It's Harry you've got to keep identifiable by reacting to Elise in a way the reader finds identifiable i.e. not a doormat. Your readers are going to absolutely loathe Elise and there's pretty much nothing you can do about that. She's your villain, and she's not the kind of "cool villain" like Voldemort, she's the Umbridge-style frustrating annoying gets under your skin literally want her to appear physically in front of you just so you can strangle her villain.

 

If OP can't write I don't think the decision will matter either way. People are saying that "regular romance" is easy to write... one look at FF.Net will dissuade you of that notion. Almost every fic on there has some romance element, and maybe 10 fics out of the 500k or so do it well.

 

lumiere, dark and twisted as a character can be utterly fascinating however I'm going to second several people on the make them interesting and identifiable.

Show us her being pushed to the edge by the Blacks and the other nasty people around her. Show her small rebellions or revenge against them so we can watch it spiral from her small and justified "getting back at the fuckers" moments like her setting a classmates prized dress robes on fire to putting crushed glass in their shoes. If we can feel a bit of "yeah, get the ahole" then even with the super twisted moments we'll still follow her (I've ready a lot of dark Harry stories where he's off the charts evil but super smart and somehow still interesting while he murders people left and right).

I find characters that cling to or obsess over one person to get boring real quick and seem pathetic and eww. The same with characters who fall into traps like this. Maybe Harry see's right through her attempt to win him over and challenges her to make it worth his while. What I thought of was Cruel Intentions and that kind of dark, twisted story.