GASP! I'm actually back with a new fanfic after all this time! Anyway, this was originally going to be another one-shot for my collection known as "Ghostly Tales", but I just wanted to keep writing, so I decided to make it a separate story.

In Undyne's eyes (her one good eye, at least), the entire day was completely normal. To cooking with Papyrus, watching anime with Alphys, and cleaning up whatever disaster was concocted during said cooking, it seemed like just an ordinary day in the life of the fish monster.

At least up until her training session.

Now, Undyne's favorite thing about training was the fact that there was never a dull moment. Mad Dummy definitely made sure of that, what with his near-constant rage, all the knife-chucking, and obscenities that were screamed.

That being said, today was certainly interesting; just not quite in the way Undyne had hoped.

First of all, Mad Dummy was not supposed to be the exhausted one. Sure, he was the one who got punched every day, but for one who couldn't get physically hurt, it took a lot to wear him out while training. In fact, now that Undyne thought about it, the dummy usually enjoyed training so much that he would always seem to have a consistent rush of adrenaline. Seriously—where did all that energy come from?

So of course, Undyne was downright befuddled when her punching bag lay limp on the grass shortly after she gave him a swift kick in the torso.

"Um…Mad?"

She fully expected Mad to hop right back up and scream at her, only to see him flinch at her voice and cringe. Something wasn't right.

Undyne frowned. "Listen…maybe we should just take a break."

Mad vigorously shook his head. "No! It's just a little headache; I'm fine! I just—I'm just…" His head lowered as he softly groaned.

Undyne wasn't convinced. "Forget it, Mad." She brushed the dust off her hands. "It's fine. I don't want you pushing yourself too hard."

Mad Dummy forced himself to stand, struggling in the process. "I'm not!" he yelled, straightening himself up. "Come on—is that all you got!?" He hopped forward, but misjudged his distance and ended up flat in his face.

Undyne suppressed a snicker. "Sorry, punk. Maybe we'll just try again tomorrow." She turned around to head back inside the house.

Mad raised his head, only for his vision to blur. He muttered something indistinct as he let himself fall back onto the grass, head pounding.

Undyne was about to open the door when she heard a rather strange noise from behind her. She glanced back at Mad, who was face-down on the grass and trembling. "Are you…crying?"

"NO!" Mad swung his head up, immediately regretting it when he felt light-headed.

Undyne raised a brow once she noticed what looked like tears falling down his face. She had seen Mad cry only once or twice in her lifetime, but this was ridiculous. "Mad, are you kidding me right now? You're seriously crying over not being able to train?"

"I'M NOT CRYING!" Desperate to regain his dignity, he pried himself off the ground. "And I don't care about training! I don't…I just don't know what's wrong with me…" He shut his eyes and tried to stop himself from shaking.

"I'll say." Undyne gradually approached him, not liking how uncharacteristically timid he seemed. She then noticed something else odd, however. "Wait a minute…" Upon further examination, her eyes widened. "Holy cow!"

"…What?" he growled, already feeling woozy from standing for so long.

"I thought you were crying; you're sweating. Is that supposed to happen?" Undyne looked concerned.

"I don't know…" Mad wobbled around in an attempt to maintain his balance.

"Mad, are you feeling alright?" At this point, Undyne didn't know why she even bothered asking.

Mad gritted his teeth. "I…I feel…fine…" A sudden chill ran up his nonexistent spine, and he shivered uncontrollably.

Undyne didn't fall for his bluff in the slightest. "Alright. Somethin's definitely up. I'm gonna get Alphys." If anyone could figure this out, it was definitely her.

For once, Mad didn't argue. He managed to take a few steps and follow her, but then he came to an abrupt halt.

Undyne opened the door, but after seeing that Mad wasn't right behind her, she curiously turned around.

Mad was standing a couple feet away, supposedly focused on something. He shut his eyes.

"You good?" Undyne asked him. "Can you walk at all? Or hop, I mean."

Mad remained silent for a few seconds before sneezing rather loudly. Undyne was startled, both by the sudden noise, and the fact that a large portion of Mad's body seemed to fling forward from the force of his sneeze.

Then Undyne realized it wasn't just some portion of his body; it was his ghost.

Madstablook lay motionless next to Undyne's feet for a while. The fish monster blinked, unsure of how to respond to what just happened. "Um…Alphys!? Could you come here for a moment!?" She called out as she stared at the ghost.

Mad finally raised his head to look at Undyne. Once seeing her puzzled look, he frowned. "Undyne?"

Undyne didn't respond; she only continued to stare at him.

Mad cleared his throat, not sure whether to feel self-conscious or annoyed. "What? Haven't you seen someone sneeze before?"

"Mad…I've seen a lot of things in my lifetime, but what just happened is completely new in my book."

"Why? What happened—" Mad flew up to meet her height, feeling much lighter than usual. "Wait. Why am I—" He whipped his head around, soon catching sight of the 'empty' dummy pieces lying next to a bush.

Needless to say, all heck broke loose.

"Wait WAIT WAIT!"

"Um…"

Mad flew as if his life depended on it. He dove into his body so quickly that it took him a while to put himself back together.

"Mad…"

"Shut up SHUT UP! You didn't see anything!" he hissed at her. He took a step forward, only to nearly fall over again.

"Mad, seriously—" Undyne started.

"Hold on!" Mad tried to hover instead, but managed to gain airtime for about two seconds before he felt something heavy drop from under him. "What—" He glanced down and shuddered at the sight of his 'body' on the ground again. "No NO NO!"

With the way he was hyperventilating, Undyne swore he was going to explode at any second. "Mad, I seriously think you should just stay put while I get Alphys…" She cautiously stepped into the house.

"I CAN WALK BY MYSELF!" Mad retaliated at he returned into his body again. This time he immediately dropped to the ground, unable to move at all.

Undyne ignored him and hollered, "ALPHYS!?"

"STAH LAHING!"

"P-Please don't talk with the thermometer in your mouth…"

Alphys sat at a chair adjacent to the couch, flipping through several pages of a rather large book on her lap. It was specifically a book on monster ghosts, one that she had bought from the library particularly after meeting Hapstablook years ago. And seeing how Alphys and Undyne practically lived with a ghost, it went without saying that this book had proven to be helpful in many cases.

"I'm not laughing!" Undyne smirked, although it was rather hard not to laugh at the irritant ghost. It wasn't that she enjoyed his misery; it was merely the fact that he was dead-set on hiding every inch of his body with the comforter he was given, yet his head poked out.

Mad growled as Alphys finally took back the thermometer, shortly before he shoved a pillow into his face. Alphys pushed her glasses up as she glanced over the number. Once she checked her book again, she looked back and forth between the two as she winced. "Oh dear…"

"Is it bad?" Undyne took a peek, but only grew more confused. "Wait, that's totally fine! That's like my normal temperature, isn't it?"

"W-well, yes, but…a g-ghost's normal temperature is a bit cooler than most monsters s-since they don't need as much thermal energy; that's w-why Mad doesn't hold up as well in hotter weather than we d-do," Alphys explained as she flipped another page. "So seeing it at or e-even near our normal temperature isn't necessarily a g-good thing…"

Already knowing all of this, Mad was only half-listening to her. "Can I go back into my body now?" his muffled voice asked from behind the pillow.

Alphys reluctantly shook her head. "I'm…n-not sure if that's a good idea. Given your temperature, you should p-probably just focus on relaxing for now."

The pillow whipped down as a look of utter horror consumed Mad's face. "You're kidding me."

"Well, seeing how you couldn't even take one full step before falling flat on your face, I say you're better off staying a ghost," Undyne chuckled.

Mad felt nauseous just at the thought. "No no no…" He pressed the pillow back against his face even harder. "Please don't do this to me…"

"Staying as a ghost is actually f-for the best, really," Alphys told him nervously. "If Undyne is right about you n-not being able to walk, then y-you don't quite have the strength t-to fully control your body right now…"

Mad screamed, although it was silenced by the pillow on his face. "SOMEBODY KILL ME NOOOWWW!"

Undyne just rolled her eyes at him. "Relax, drama king. It's not like anyone's gonna see you like this."

Alphys looked even more anxious. "J-Just please try to calm down…we d-don't want you to bring your fever up even more."

Mad didn't seem too calm, but at least he wasn't yelling anymore. Still, they could see him trembling a lot more than usual.

Undyne swore she heard Mad mutter something under his breath. Assuming it was some sort of insult, she narrowed her eyes and leaned forward to hear him better. Seconds later, she froze. She wasn't hearing things this time; he was actually trying not to cry.

Wondering if Alphys could hear him as well, Undyne looked at her for help. Luckily, the scientist quickly spoke up. "B-But…at least this way I c-can stitch up your body and make it good as new for when you get better!" she told him hopefully.

Mad was quiet for a few seconds, most likely to calm himself down enough to actually speak. "Th…thanks, I guess…" he mumbled, although he still refused to show his face.

"Just g-get some rest, a-alright?" Alphys took her book and started to walk out of the room. "I-If you need anything, just ask…we'll b-be in the kitchen nearby."

Undyne watched her leave and turned back to the sick ghost with a sigh. "Well…" she began, not quite sure what else to do. "Get some sleep, punk. We'll wait a few days after you're better before going back to training, alright?"

Mad tightly shut his eyes and curled into a ball. "Whatever…"

Undyne followed Alphys into the kitchen. The scientist still looked a bit concerned, head buried deep in her book.

"So…what now?" Undyne asked her.

"I…I'm still trying to f-figure that out. One thing for sure, I'm j-just worried about his fever. It'll only get worse if he k-keeps getting riled up like that…"

Undyne began to regret messing with him earlier. She glanced back at Mad, raising a brow. "Hey, he ain't contagious, is he?"

Alphys was already way ahead of her. "From what I've read, n-no. Ghosts are only contagious to other g-ghosts."

"Huh. Ghosts are weird." Undyne scratched her head as Alphys set the book aside. "I wish I could do something to help, but when it comes to ghosts, I know diddly squat…"

"T-To be honest, I only know from w-what's in my book. And even then, I'm n-not entirely sure I know a whole lot myself—" Alphys paused for a second. Her eyes suddenly lit up in realization, and she turned to Undyne. "B-But we know someone who does!"