The Patronus Charm

Oleandra needed to put as much distance as she could between herself and the Dusk Elves before they discovered she was missing; she would consider her next move once she was safe. For all she knew, the Elves had taken her back to Svartalfheim, which meant she would be stranded. Forever potentially, without her friends to help her use the Realm Travel Spell or without the Gate between Worlds.

She shook her head; what had she just told herself? Focus on the task at hand. Escape, and live to fight another day!

Peeking around the corner, Oleandra found that the guards hadn't moved an inch. Well, if she wasn't going to stand there all day with them, she might as well try something. These Dusk Elves seemed rather averse to light, weren't they? Oleandra stored her Hand of Glory inside her pouch, plunging her vision into darkness once more. 

One last deep breath. She tried to stop her aching hands from shaking so much; if she dropped her wand, she was dead. Her shoulder hurt too, where she'd been stabbed, but she couldn't afford to rest. She was as ready as she'd ever be.

Oleandra dashed around the corner, towards the two guards. It was a straight line to the exit from there; there shouldn't be anything to trip on in the total darkness. The guards reacted almost immediately, pulling out their daggers, but unfortunately for them, they weren't going to be able to put them to use!

"Lumos Maxima!" shouted Oleandra, shielding her eyes in advance.

The effect was immediate; the two guards screamed and held their eyes; they'd effectively been flash bombed. Oleandra managed to quickly incapacitate them with two Full Body-Bind Curses without biting her tongue. At last, she was home free!

Oleandra kept running and burst out of the door, but no sooner had she crossed the threshold that a loud alarm started blaring. The Elves must have had some sort of Caterwauling Charm on the door! She briefly looked back to see if she had any pursuers, but so far, nobody was coming after her.

"Oh, Hel," Oleandra swore. She could still see the solitary mountain around which the Dwarfs had built their city from where she was. The good news was that she was still in Nidavellir, which could be considered neutral ground, but she was hundreds of miles away from the City of Gates. The Dusk Elves had taken her to an abandoned mine at the foot of the mountain range, where they had presumably set up their spying operation, or whatever it was they did here in the Realm of the Dwarfs. 

This was very bad news indeed; Oleandra had very few supplies to walk such a long distance, not to mention she'd probably be chased the entire way. If she turned back and hid in the mountains, then she'd be no closer from home. Under normal circumstances, she'd have used the Tree-Porting spell to teleport to the city, but unfortunately, the altered form of Berkana was still missing from her repertoire, and she hadn't seen a single tree the entire time she'd been in this world.

She ran and ran and ran until she could run no further. There was nowhere to hide; only tall grass that reached up to her knees. She might be able to escape detection by lying down on her belly, but if the Elves had other ways of sniffing her out, then she was dead!

To Oleandra's dismay, a few hours later, the sun began to set. Ordinarily, she would have been overjoyed to finally get a chance to examine the firmament at night, but night was precisely the time at which the Dusk Elves would be at their peak! It's not as if they were vampires or anything, but they operated better under the cover of darkness. And besides, she didn't have the time to be stargazing. 

Still, nobody seemed to be after her, which was very strange, and quite discomforting. As she walked towards the city, Oleandra looked up at the night sky, trying to locate the particular constellations that formed the runes she needed. 

All of a sudden, out of the corner of her eye, she saw it. A gentle ripple. Stars disappearing and reappearing. Was something darker than black moving in front of the stars? And then, her heart sank. Oleandra realized she was done for; unknowingly, she'd been surrounded.

At least twenty Dementors were floating quietly above her. Strangely enough, even with their number, Oleandra didn't feel the usual coldness and despair they usually inspired. Most people would have been reduced to gibbering messes curled up in the fetal position, had they been facing twenty Dementors! Was it because she'd been hurt so much that she had nothing more to give?

Oleandra felt a tinge of hope light up in her chest. If the Dementors' mental debuff didn't work, then she'd rather face a thousand of them than face the Dusk Elves' sharp knives! Happy thoughts, she needed to summon happy thoughts. She closed her eyes and pictured herself leaving this place and going back to Hogwarts. Everyday life, laughing and squabbling with her close ones, that was what made Oleandra the happiest. She opened her eyes again and raised her wand; the Dementors were descending upon her.

"Expecto Patronum!" she yelled, pointing upwards.

Something felt different, this time. Silvery light gushed out of her wand towards the sky, then fell back down, filling with the air with lustrous droplets of magical rain. More and more came out, and the rain of silver light accumulated at her feet. All sorts of aquatic animals, all made of the same radiant light, began emerging from the pool, no, lake, she had created. Ducks, geese, swans, turtles and fish of all kinds began to take form.

Something clicked within her. This had something to do with the very core of her being. This was Oleandra Greengrass! The individual animals weren't the true form of her Corporeal Patronus; it was the lake itself! The lake was her domain, her consecrated ground. No Dementor could enter it, but at the same time, it had a fatal flaw: the Spirit Guardians couldn't be sent outside the lake's periphery.

Oleandra frowned; something was wrong. Her Spirit Guardians spiralled up into the sky and starting attacking the Dementors, but something was… off.