Even Norma initially reacted that way in Tales of Legendia, so it's natural that Giles would, especially with the whole vampire thing in his home canon. The really unfortunate part is, when she gets her memories back, Grune isn't going to expect things to change between them at first. It's the only way she's as naïve as her amnesiac self. But boy will she figure that out in a hurry, and then the results will be, well, this.

I'm really, really glad I manage to inspire an emotional response in you. That's pretty much the highest compliment anyone can pay me. ♥

And actually, I have a number of Awakened!Grune fics I just haven't posted on here yet, so there'll be more in this vein fairly soon.