"Corrin, wait!"
Camilla cried out in dismay as Corrin stormed out of the room. Was it something she said? She knew in her heart that it wasn't her fault, but she still worried regardless. Seeing her sibling in such discomfort pained her greatly. Corrin needed her support. She moved to follow but stopped, feeling a hand on her shoulder.
"Leave Corrin for now," her older brother Xander advised her, "the last battle was particularly hard on them. Give Corrin some time alone."
Camilla nodded, heeding Xander's advice. Corrin just needed a little time alone...

Ten minutes passed, but to Camilla they felt like hours. She had knocked on the door of Corrin's treehouse, but received no answer. Knowing her sibling was in there, suffering on their own, Camilla knew she could not leave things the way they were. She was more than strong enough to break down the door, but such an action would only further distress her dear sibling. But she needed to get in there. Was there some other way?
Spying a gap between the floor and the door, Camilla had a flash of inspiration...

Alone, Camilla retreated to one of the lessused rooms of the castle. There she grabbed what promised to be the solution to her woes a single, small vial of potion. When told that it would reduce the size of the one who ingests it, Camilla initially struggled to think of a use for the thing. Yet now, it seemed to be exactly what she needed.
Camilla hesitated, worried that it might be poison, but only for a moment. Corrin needed her. Thinking of her distraught sibling, Camilla lifted the vial to her lips and drank the whole thing. Its bitter taste was not displeasing to her, but she wondered if it would have any effect. That was before her field of vision sank ever so slightly downward, like she had stepped out of her boots.
Is that it? Camilla was about to say, noting how everything around her was just barely larger. But then she felt herself recede again, stronger this time. She was significantly shorter, but this was still not enough. Luckily she experienced another shrinking spurt just moments later. However her fingers slipped, and the vial fell down to the floor. Camilla bent down to pick it up, only to suddenly shrink even more. Each of the brief episodes of shrinking was stronger than the last, until her size was continually halved, a dizzying rate of reduction for the worried royal.

Eventually it came to a stop. Camilla was now a tiny fraction of her original size, mere inches tall. The empty vial of potion that had once seemed so small now dwarfed her tiny frame. Bewildered by her sudden change of height, Camilla looked around her now massive surroundings. The room had seemed so cramped before, but now it looked larger than the whole castle.
Quickly getting over her initial shock, Camilla smiled.
This will do nicely. She thought to herself. I may have some trouble getting up to the treehouse now, I suppose. But, once I'm there, I'll easily be able to squeeze under the door. No problem for the littlest sister...