@rotstich92
I don't really think there's anything about the father being an excellent magician, which means he'd still need the help of Daphnee's older brother, the magician from the tower. And he explained it as being between two people, so if the father was involved in that, it'd happen after Keira was already dead for a while, which doesn't make sense to me to choose a dead third party to have memories.
You could argue that the two, father and magician, teamed up afterwards to do the same once again and change the outcome of the original timeline, but the magician was too weak since he'd already done it once before, hence the fragmented memories compared to Keira's intact ones.
I'm still curious if the thing she saw when she went back in time ages ago was another spirit like a fire spirit, or if that was just the magician she made the contract with, since that could be a major change, just imagine if she awakens a completely different spirit that was unknown until now.
Cosette herself strikes me as a weird one, the story is set up so that she could easily be a real daughter, however all the undertones scattered about hints to something else.