Desperation caused her to use her wand. As she used the roaring fire in the middle of the woods to warm up her frozen body, she considered the very real possibility that she would be found by one of the Dark Lord's minions. She was low enough that the thought of being dragged back to captivity didn't even sound like a horrible fate. At least with the loss of her freedom she had a warm bed and enough food to eat. She might not have cared for her master's incessant personal attention, but at least she wouldn't have to worry about getting sick and dying alone in the snow. She had the freedom to use her wand even if her orders were hardly pleasurable at times.