@Sera21 - there are of course varying degrees of 'dark'; my aim wasn't ever to go pure-evil dark. I don't think I could go pure-evil dark, my heart just wouldn't be in it. Funnily enough, I just wrote a 'Voldemort taking pleasure in death' bit yesterday (will be awhile before that chapter is published). But, past that point there really won't be any more like that, it's just not something I enjoy enough myself (not that I think there is anything wrong with anyone who does, don't get me wrong). Just getting through that one bit was pretty tough for me, and I had to redeem it a bit with Snape afterwards (doing something that was actually kind, but not out of kindness; it was calculated on his part).
LOL, also didn't realize I'd made Voldemort sound like a bodice-ripper protagonist; when I said muscular, I meant the way Ralph Fiennes' chest (what you see of it) is in the movies. He doesn't have a brawny chest, but it is defined; it's just not over-developed like a bodybuilder's. Not sure how else one describes that (suggestions welcome).
As for the insane part; I actually wanted his side to succeed in the end, and I couldn't really see how that could happen with a truly insane leader (Hitler notwithstanding - Voldemort seems very much based on him in many ways. Especially the dichotomy of wanting a pure race that he doesn't himself fit; Hitler not having blonde hair/blue eyes like his ideal Aryan race, Voldemort not being a pure-blood himself. But, Hitler's success wasn't permanent either - my aim in this one was to make it stick, and unless he just killed off all but his own followers while following the insane path, there would always be an uprising/resistance). Snape's aim is to convince him to go at it in a way that leaves the resistance not much to 'resist' in the end, which sounds like it won't be your cup of tea, really. (Trying to spare you any further disappointment, don't want you to keep reading hoping it will turn darker.)
I'll probably not write any more even loosely described as dark past this one, is not my thing and honestly I've been very surprised at the overall reception it has gotten up to now. Thank you for taking the time to review it and to review it honestly as well, there are still some things I can take from that into other stories later even if they're not in this vein.
Edited to add: Also, on him charming Lavender to get what he wanted - he has done that in the past. It's how he obtained the locket, goblet and diadem (locations of, anyway). I couldn't actually see him wanting to have his intended consort last rather than first; he was after all looking for more than just someone to have his child (one assumes Bellatrix could have given him that, and would have no matter how Rodolphus felt about it). He was looking for someone to corrupt, to have his child, to take their soul, and also to be first among his servants. It'd be hard to consider someone 'above' you that you'd raped repeatedly.
A lot of the motivations in this story are psychological like that, perhaps too subtle. For me, his 'charming' of Lavender was twisted, but I can see how it might not come across that way well enough.