@CTG: First, as to unsubstantiated, as I said earlier, they have been proven in other threads -- I found proof for that before I even joined CV, in one of the first interviews Hopeless did. He requested characters for this book and was told -- even though they weren't going to be used by anyone else -- that he wasn't allowed to touch them. Several of the characters were from books which routinely underperform financially. I'm not going to bother arguing it because it's something that, again, has absolutely been established with links elsewhere.
Mettle's death served the book, not Mettle, not Academy fans. If you call that "meaningful" then our definitions are simply wildly incompatible. When you have the author promising fans of a character that should that character die, you'll have been respectful and you'll have honored the character's legacy -- and then kill the character in a way which only serves your selfish purposes as a writer, then no, you are not writing a meaningful death. And nothing whatsoever can be defended about the second death. None. There is no excuse for having killed anyone there -- she could have simply been injured, or just realized it was a roof. And if someone had to die, then that absolutely could have been a red shirt type new character, not a previously-existing one.