I would actually hate it if Pink turns out to be the villain because I kinda like her already, but I do think that based on the way other characters treat her, she will be angry at some point.
She looks like she doesn't belong in the story - best friends of Red and Chloe don't treat her as their equal, everyone loves Red and Chloe but nobody says anything about her, all her lines are her inserting herself into the song rather than already being a part of it and she's always talking about herself because no one talks about her, Red seems to be the Queen's favourite child and the Queen doesn't even pay attention to Pink while she's in the same room with them. Since Red didn't have a sister in the original timeline, I think that she will neglect her because she doesn't know how to be the bigger sister and that will make Pink angry. Their personalities are very different and Red will probably avoid spending time with Pink because of that.















