What if, in Chapter 24 (sectumsempra) of HBP, harry took a little felix felicis. This led him to use Sectumsempra and hide his book, which showed him the vanishing cabinet.
Unrelated, but do you have Farfalle/Timeline's pfp? I should probably ask this in WoF wiki, but I honestly don't really care since you're from WoF wiki.
