Yes, I’m aware that the site her brother posted on is full of assholes (but so is this website). And if it weren’t for the screen caps, and Rose’s behavior following this information surfacing, I wouldn’t believe him. But the person in question appears to be the real deal. Rose took down all information regarding her being Native American, made a plea to her brother on Twitter, and her book deal was cancelled, very shortly after the person came forward. I think it’s safe to say the KF user is the real deal. I wanted to believe her too—if only because a metalhead Undertale fangirl being the author of the best troll fic in existence would be completely amazing in my book—but the evidence that she is not who she says she is is overwhelming.
And even aside from all that, I didn’t buy that she wrote this troll fic to somehow find her long-lost brother. And given all this new information, it’s likely she lied about writing My Immortal too. If you ask me, the true author will remain a mystery forever, as it should be.