Author's note: Once again this is written with the Frozen-Harry Potter crossover "Exolvo" head cannons in mind. If you are lost, you'll find a link to the master post on tumblr on my profile. There's lots of folk crafting amazing stuff for this setting, well worth a look both at the master post & in the tag where new creations (stories, art, ideas) get shared.

Part 1: First meeting.

It was a late autumn evening when we first met. I could feel the magnetic pull of the aurora in my joints, but you couldn't see the lights from Saint Mungo's Hospital. Too many illuminations, too many ceilings, and most importantly, too many patients: it was enough to wear an old troll down. It had been a long day, as they tend to go. I was just finishing off, my daughter Bulda fussing in my office, when a wizard, one of the important ones, knocked on my door and asked if I could spare just five more minutes of my time.

"He's already late for the family reunion by fifteen minutes, what does-" I shushed Bulda, raising my hand. I considered this Dumbledore an ally of weight for our kind. It would not do to give him cheek. She rolled her eyes, but became quiet.

"What can I do for you?" I asked, stroking my beard of straw. I looked him up and down, trying to sense the seriousness of the situation. Dumbledore was not the sort to idly ask for help. His eyelids looked heavy with fatigue, but that was not unusual. Most wizards that were as highly regarded as him were hard workers always trying to squeeze the most out of their time. What was unsettling was the way he muttered slightly under his breath, his eyes constantly flicking back to something in the corridor behind him. Something was worrying him, and by the sag of his shoulders, I could tell that whatever had happened saddened him.

They say trolls can't read people. Hah! It is people who can't read trolls.

Dumbledore didn't take any notice of Bulda as she rolled out onto the small balcony adjacent to my room. More of a cupboard than an office, it was the luxury of being able to slip out for a brief breath of fresh air that kept me from asking for any other room. Taking off his glasses, the wizard before me rubbed at the bridge of his nose.

"What is it Albus?" I asked, hobbling closer. He wasn't usually one to be slow with his words.

"I… I'm going to need you to change a young girl's memories for me."

I tilted my head, waiting for him to elaborate. It wasn't an unusual request. Memory alteration was my specialty; it was what gave me the position here at Saint Mungo's hospital for the magically injured in the first place. Rare was the day when I wasn't required to alter some patient's memory for their protection or wellbeing.

"Her happy memories…"

"Oh." I frowned, confused, but not off put. I knew that my old ally would not request this of me without a good reason. "Happy memories of what exactly? And what to..?"

"Wandless magic," he whispered, putting back on his specs and hiding his eyes. "Ice and snow, as far as I can tell. Keep… Keep the memories happy, but the child is not to know that the element was summoned by her sister."

Eyes wide, I paused a moment. Wandless magic was such a broad term. I had to ask.
"The sister… Born or… cursed?"

"Born."

Hearing that word was a balm to my old heart. Children born with wandless magic were a gift to the world, no matter how dangerous they could become. Wandless magic born of a curse would be a completely different landslide to deal with.

"Bring the child through." I nodded, hobbling towards the small examination table opposite my desk. I could hear Bulda muttering as she rolled into a ball outside, the cold breeze from the door giving my tired bulk a second wind.

"Thank you, Pabbie," opening the door and waving the family through, Albus Dumbledore nodded gravely before departing. "I shall leave you to it. I have some quill-pushers to handle."
I did not envy him the task of sorting out the paperwork for an incident like this.

The second wind from the balcony was much needed. The child came in sound asleep in the arms of her mother. No older than five, she had a lock of hair amongst the shock of ginger that shone white as ice. She'd obviously been partially treated already, my hand tingling as it passed over her right eye from the magical residue. It had been a close call. My heart sank as I noticed the sibling, only a couple of years older, shrunk in upon herself by the doorframe, huddled against her father's legs. It was clearly an accident… Oh, how many families had ended up in these very corridors after a tragically unforeseen mishap?

My features remained stoic as I waved my hands in the air, summoning out the memories that required my touch. I needed to focus. The memories I had to change were multiple and deeply ingrained.

Humans remember fear and pain strongly, sometimes to a debilitating degree. I was used to fighting memories that would not be forgotten. I have lost count the amount of times I've had to hunt out a happy memory so nearly forgotten in order to knock the bad ones loose. This girl, this Anna, she…

Altering all these memories of her and her sister playing, it was like trying to uproot a mountain. The scenes in her mind of snow play and fun were all so full of love and trust; it was a true testament to the beauty that had always drawn me to humans… despite their many tragedies.

Fortunately, most of the memories were easily enough altered: a small tweak of the décor here, an added detail there and another removed from this one… The hardest to change was the last, the one where the infant's joy had reached its crescendo before a blast of cold suddenly turned off the lights. I gripped my crystals to power through. This memory could not be changed. This memory would need to be locked away, somewhere safe. It needed put where it couldn't be reached lest it caused the girl physical harm anew.

Remembering the Pensieve I had helped Dumbledore restore, I wrestled the recollection of the incident into a silvery thread. It glowed, golden light showing how bright and warm it had made the girl feel, the blue tip at the end the only indication that things had gone sour. Ripping a vial from the cord around my waist, I downed its magical contents before using the crystal container on the last memory. It fought and lashed out, but somehow I managed to get it in, flowing smooth and silky, the line to the girls mind pulled taught until I cut the memory loose.

It had taken more than five minutes. Bulda was going to give me an earful.

Leaning against my stool as I dropped down to the floor, the only thing that remained for me to do was to find a safe place for the vial. It glowed still, as golden as the magical energies I kept stored upon my belt. My elbows ground painfully, reminding me exactly how long a day I'd had.

We trolls are very particular about memories. You could say we're particularly possessive: a memory only ever belongs to one person. No two points of view are alike. If one has to be taken away from its owner, it needs to be in the care of the person they'd trust the most with it. After seeing the memories I had just sifted through, I had no doubts.

"She'll be alright," I said, nodding to the mother as the girl shifted into a more comfortable sleeping position, a small smile on her face. She would be having pleasant dreams for a while, as her mind adjusted to the changes I'd wrought. Hobbling towards the door I bowed politely to the father, before turning to the other daughter. She was anxious and tired, it was easy to tell. A thin layer of frost had formed around her feet. "Elsa, I would like you to keep this."

"Is… Is it?" Hesitantly she allowed herself to unclasp one of her hands from her chest, her father squeezing her shoulder in reassurance.

"This is her memory of your magic, yes." Taking her hand in mine as I gently put the crystal in it, I focused on her face, willing my stony features to express the seriousness I truly felt. Her father had knelt down behind her, his face hopefully a good mirror of mine. "I can trust none but you to keep this safe."

"She won't remember my magic?" So young a girl, the blonde's voice sounded weak as she realized exactly what this meant.

"No. She won't. You'll need to keep your powers hidden." Her eyes were cast down as I confirmed what she feared. I continued however, feeling the need to reassure her somewhat. "There is great beauty in your Magic, Elsa, but great danger also. You'll need to learn control."

"We'll help her." Her father agreed, hazel eyes flashing with protective ferocity.

As the family left my office, I felt heavy and weary, wearier than I had felt since I had moved my family here from Scandinavia. Only the small thank you I heard whispered as they left helped me feel lighter over what had just transpired.

"Wow…" The small voice of a boy expressing admiration was not what I had expected to turn around to.

"Bulda, what?"

Bulda was now standing at the door to the balcony, a small blond boy standing before her and what looked like a young reindeer behind. The boy, his clothes a tattered mess of rags and castoffs, gave a shy wave.

"Look at these cuties. Can we keep them?"

The boy didn't say much as my daughter gave him a bone crushing hug.

(End Part 1)