Ok this is going to be a bit weird but a lot of this has to do with Demonreach and some of the myths involving Merlin. The idea would involve Harry being hurled back through time but the main reason I think about it is that Demonreach seems to recognize Harry and he feels a strange connection to everything. Also things are bound but are getting loose. The idea here is admittedly a bit iffy but if Harry was somehow hurled back he could re-link with demonreach, he would know it and it would meet him for the first time. Merlin was said to be able to know the future by remembering it, now this could be Merlin interpreting time backwards OR it could be Harry rememebering key events and handling things that way. Keeper of swords, he'd got that down. And he could learn what he needed to learn then and come back to the present with a story no one would believe and that hurts his head in terms of causality
I could see that, but I hope not. It seems too circular and like a cheat. It is difficult to do time travel/time displacement well.
