Ok, so in the orginal tale of The Snow Queen we know that an evil troll created a mirror which made everything in it look ugly and froze your heart, obviously I could never picture Grand Pappie creating such a mirror, but do you think there could have been an evil troll of the rock troll tribe who rebelled aganist them and created the mirror or something like that, just an idea, or maybe the mirror was created not by a rock troll, but by regular trolls like the ones seen in Snow Falls but if Once was going to do that they would probably use a rock troll since they are from Frozen
P.S. On an unrelated note don't you think that Grand Pabbie sounds like Merle Ambrose from Wizard101