I just finished rereading Ghost Story, and was struck by an apparent contradiction.  Consider these two assumptions:
1) Creatures of Faerie cannot tell outright untruths.  They can deceive, but it can't be by outright lying.
2) Uriel would not lie.

Now consider that at the end of Ghost Story, Uriel accuses Mab of outright lying.  How long will it take Harry to notice, and how will he resolve this contradiction?

If it turns out that Mab can lie, then the whole Spencerian culture of Faerie is turned on its ear.  Many actions and statements of Mab -- and Lea -- and several Summerfae -- suddenly become incomprehensible, and everything we thought we knew about dealing with Faerie is invalid.

On the other hand, if Uriel would lie, then his assurance that Mab cannot change Harry is invalid.  How will that affect Harry's future interactions with Mab as her Knight, and how could he make his independence stick?  Will he have 300-600 years of constantly fighting to *not be a monster* to look forward to?  (I mean, in addition to the "normal" temptations of a mortal wizard.)

Interesting times ahead...