UB-50 - Hisui

Ailment

From behind them, Machamp and Swirly exchanged a few snickering sounds which brought Dren back to reality.
"Now that you are sorta fed, we should let you rest. Here." Dren spoke softly to the Golbat, offering the Ultra ball once more to the beast.
With a little more strength and far less hesitation the creature immediately bumped its head against the capsule, triggering the return mechanism before being sealed safely inside. Dren held the ball in her hands, purring slightly as she placed the capsule into her satchel for safekeeping.
"Nice. Did you want to... come for that walk with me?" she asked Ingo, completely oblivious of how flustered he seemed.
"Perhaps we ought to make our way back to the Highlands." Ingo mumbled in reply, his eyes glued to the ground.
"Oh. Sure." Dren was confused and slightly hurt, but she couldn't say no to the Warden - he seemed to be the more rational and wise member of their two-person party, after all. She and her Goodra assisted in finishing up the packing before setting off with Ingo and Machamp to head home.

The long trek home was incredibly uneventful. Thanks to Machamp and Goodra - who both opted to simply pick up their respective Trainers and carry them on the final leg up the mountain - there was no need to set up camp. In the end, they arrived back at Ingo's little hut with Machamp cradling a snoozing Warden and Swirly carrying Dren upon her shell. It had gotten late fairly soon after they made it up the mountain and Ingo's body seemed to give up staying awake. Dren had initially wondered if she ought to wake him but he seemed so... peaceful in his sleep. She dared not disturb him if it meant breaking him out of that serene calm. It made her wonder how much sleep he had even managed to get in the tent out on the Mirelands.

Instead of waking him once they arrived at the door, Dren simply chirruped to Machamp with her arms aloft - the Fighting-type seemed hesitant, but upon Swirly communicating her strength, Ingo was placed gently into the waiting arms. The two Pokemon watched with vague awe as the seemingly meek looking woman changed form, opened the front door with her tail, and carefully brought the sleepy cargo into the yurt. Only when she had laid Ingo to rest upon his bedroll and removed his heavy satchel from his back did Dren set her own satchel down and return Swirly to her Pokeball. With a quick glow, Dren hastily resumed her human form - but only for a moment.
"Keep an eye on things. Please." Dren whispered to Machamp as she quietly left the yurt and closed the door behind her. The Pokemon eyed her with a puzzled stare but opted to simply obey the instruction. The beast flexed her four arms to signal her acceptance before watching as Dren's wings burst forth from the flesh of her arms, lifting her off into the night.

Ingo awoke to find the little mountainside hut empty. The yurt was illuminated despite the lack of lit lamps, the glow warm and soft. The Warden stretched his arms with a loud yawn, a groan escaping him as his spine clicked and ached.

"I welcome you into my clan, gift you the title of Warden, and this is how you repay me?"

Ingo jolted out of his bed, scrambling to find his hat as his eyes landed upon Irida, the Pearl Clan leader. What in Sinnoh's name was she doing here?
"M-Miss Irida!" Ingo greeted, his brows furrowing as he failed to locate his beloved cap, "I must admit I... don't know what you mean. Have I done something wrong?"
Irida stared blankly before a male voice erupted from behind Ingo.
"You're housing a monster. Don't you think we need to know about these things?" Adaman snapped, startling Ingo as he appeared from seemingly nowhere, "How can we keep our clans safe with you keeping dangerous creatures around?"
"I-I'm sorry, I don't understand." Ingo muttered, abandoning his hat search to hold his hands behind his back. He bowed his head in an attempt to show respect but the rage of the two clan leaders remained fierce.
Irida poked a finger into Ingo's chest with such force that he felt pain radiate through his ribcage. "We know about that monster that fell from the sky. You've been keeping it safe, feeding it, bathing it," Irida snarled, her usually youthful face riddled with fatigue and anger, "what happens when it grows too strong? It will kill you first and then come for us all."
Ingo opened his mouth to speak but Adaman's booming voice silenced him immediately. "How do we know you aren't one of those things too? You didn't come from Hisui. You could be just like that... that thing."
"That's not even remotely true," Ingo pleaded, his eyes glued to the floor as he felt himself panic, "I would never endanger the people of this land. Their safety comes first, always. Dren is harmless. Please, she harbors no ill will against your clans!"
The Warden paused. Irida and Adaman grew silent. When Ingo looked up, the two leaders were gone - as if they never existed in the first place. Even more puzzling was the sudden appearance of a tunnel in place of the yurt's door.

Ingo stepped out into the dark tunnel with slow and wary steps. The tunnel was incredibly wide with two sets of unusual pathways cast in metal and stone running parallel to one another all the way through, something that seemed so familiar and yet so alien. The word 'tracks' came into mind but that was as far as Ingo's thoughts could get before he stopped with a startled gasp.
A copy of himself, dressed in white, lay motionless upon the tracks. Ingo darted forward with a panicked cry before a shrill shriek stopped him.
Dren, wings revealed and flared, stood over the body with dark stains coating her mouth and throat. Her eyes glowed vividly, a sickly green hue that seemed to bore deep into Ingo's very soul. She crawled forward on all fours, her wings trailing behind her like a great monstrous Noivern's, before she snarled at the Warden. The dark stains across her face began to glisten red in the dim light.
"Dren! What are you-" Ingo began, his voice choked out by the sudden shock of seeing his alien friend bite down into the unconscious man's flesh, tearing at his throat with her teeth like a feral beast. Ingo was paralyzed - he couldn't do anything but watch in horror as Dren all but consumed his identical clone.