Oh, Carole, thank Merlin you posted the second chapter! I read the first chapter ages ago, thought it was really interesting, and kept checking back for the next one. And now you have it up! I hope you'll follow with the next one soon - I'm hooked!
What I find so great about this fic is how you've shown Lavender's depths as a character, rather than taken the easy route and have her batting her eyelashes and giggling. There aren't many stories with Lavender, and more-so with her as a decent character. I also like how you show her reluctance to re-join the DA; not because she's a coward, but because she promised her father. It's nice to see that she's genuinely concerned for the Trio, Dean and her mother. Do we hear anything about Mrs. Brown in later chapters?
Another thing I find interesting is your portrayal of Blaise. I like the idea of him being a half-blood and sympathetic to Lavender's plight, though I have to wonder about his intentions towards her. Is it just merely a physical attraction or has he been admiring her from afar? He can't know much about her, really. Or is he just using her? Hmmm...
I find nothing to correct in this chapter, to be honest. I think your characters are all very IC - especially Ginny and Neville. I think you portray her reactions very well and how easily she flares up. I like the way you show Neville's transformation into the group's ringleader - it's a side we all knew he had, and it's great to see him being so brave.
Overall, a truly original plot-line, a well-written and interesting story and I can't wait to read more! Your work never fails to impress me. Hopefully, though, it won't take as long to update?