Rosemary approaches her sister in tears after being told that she won't be able to attend Gryffindor's Victory Party due to the fact that she rooted for Hufflepuff as opposed to her own house. This might seem like an odd thing to cry about... until you realise that Rosemary wasn't crying because Susan won't be able to go to the party. She was crying because she's afraid that Susan is going to adopt that same ridiculous amount of pride. Think about it. It's never said that Susan was one for violating the privacy of others, at least until she stole Rosemary's diary.
Ollivander really wanted to get rid of that wand back at the shop, didn't he? According to him, the wand has a mind of it's own and it chooses the wizard. Just let that sink in for a moment...
Susan was attacked by a werewolf at age four... the same age that Remus Lupin abandoned his duties as her godfather for reasons that he refuses to explain...
