We like to talk about what Harry finds once he gets there but not so much the motive behind it, unless it was an accident.
Probably because Jim told us the motive.
A possibility, but we know a time travel book is coming... Right before the BAT... I think that Drakul making his single appearance in the entire series, and grabbing someone who happens to be talented with time magic means something... probably not something good.
Jim hinted that there would be a revenge on the Black Court book coming soonish, so we'll probably get Drakul before the time travel book.