Growing up Estelle was always a little trouble maker with violent temper and a demonic type of behavior, probably from Spikes side with how tempered dragons can be. Rarity called her free spirited, until she started climbing on the walls and threaten to eat the other children's pets. Ember suggested to leave her in the cave of solitude, where they'd put misbehaving hatchlings to fight it out with other hatchling to release all their energy and to chill the heck out before they came home. Which helped , and no she's a normal energetic toddler.