Spitfire sighed as she put on her uniform, the covering of her body locking her away from the world, while the morning sun blazed in the sky overhead. She was content with her life, Captain of the Wonderbolts, and all around, a well respected pony, and yet, she still felt like something was missing, like she should be bigger than she was.
Distracted by her internal thoughts, Spitfire pricked herself with her newest medal, given by Princess Twilight herself, the thing was shaped like a star, and it caused Spitfire to cry out in surprise. She pulled the badge away quickly, for some reason, it felt hot now, like it was being held over a fire or something. She blew on it to let it cool down, before finally sticking it on her chest beside her other medals, and then moving towards her home's gym for morning exercises.
She barely made it three steps. This was because, with every step towards the door, it seemed to grow closer like she was leaping towards it. It took the captain a second to realize why, as her hooves came down with louder, and louder clacks on the wooden floor. She looked down when one of those clacks became a crack instead, and found that her hoof had literally smashed its way through the floorboards.
At first, she thought it was just this lousy construction. The Academy was pegasi built, but they were more used to working with clouds than wood. She was quick to discover that wasn't it though, as her head painfully slammed into something, and she ducked down to rub it and look upwards to find the ceiling, one of those high, vaulted ones, was now literally right above her head, and it was growing closer all the time.
Her eyes went wide, and Spitfire's mind raced as she tried to think of what to do. Of course, this was so far outside her training, her thoughts just kept whirling around in circles as she first ducked down onto her knees, and then head to curl up into a ball to avoid touching the ceiling. That only helped for a few second, as her body soon became so large that the room started to get cramped. Her but press painfully into book shelves, and her hooves crushed her bed against the other wall.
Outside, everyone could see the captain's quarters start to bulge in odd ways. The walls pushed outward, and the roof went up. This was odd enough that it attracted a crowd of pegasi to watch, with none being brave enough to approach it, until the roof and walls blasted apart with cracking sounds like small explosions, and out of that rubble came a huge cry of relief, along with an equally huge Spitfire in her captain's uniform.
Spitfire's wings flared outward in relief as she was let loose from her bindings. Of course, her mind was fast to realize that she was both, a bit too big to command now, and worse, she was still growing larger. In fact, now that she was outside, her growth rate seemed to have stabilized at a good doubling every fifteen seconds by her measurements, meaning she went from the ten meters she'd needed to bust out of her home, all the way up to a hundred and sixty within the span of a minute.
Her size allowed her to look out over the whole Academy, and her hooves, now as large as the buildings on site, stamped on the ground with earthquake like tremors. She realized she needed some altitude to get herself away fro everypony, and so flapped her wings hard, trying to rise upwards like a rocket, taking herself into the air.
She figured at she'd hit the atmosphere's edge in a second or two, but oddly, her wings didn't seem to stop finding air to push against, and so she kept going upwards, until at last, she just stopped, and then looked around. She was in a black void, with nothingness all around her, except for the light of the stars, and her eyes shot about in every direction.
She wasn't panicking yet though. She was a Wonderbolt, her training told her just to try and fall towards the ground when she couldn't see any landmarks, and somehow, irrationally, that training was still kicking in, letting her stop her wings for a moment, and then just drift. It kept her mind from spinning off into thoughts of how she was still breathing, and how she would find her way home.
Then she felt it, something grabbed her. Four somethings actually, with golden, dark blue, pink, and purple light surrounding her, and dragging her through space until she found herself right next to a big burning fire. It took her a few seconds to realize that the orb she was floating next to, one only slightly larger than herself, was the sun. The Princesses had used their magic to put her in the sky next to the sun, and she was now one of the biggest things in the sky.