A/N: Waterfall is going to be much more slower-paced than Snowdin and the Ruins because I have to share it between Percy and Melody. That means long chapters ahead!

Also, if you've read the cringe that is Somebody Came, you'll know that I gave Monster Kid male pronouns. However, in this story, they are going to be gender-neutral, like certain human children. Monster Kid's gender isn't confirmed so whatever.

Happy reading!

~Melody~

Melody had to admit Waterfall was quite beautiful. It was blue with various waterfalls coming from the ceiling. A flowing river was beside the path. Small crystals were on the path, glimmering. If only it wasn't so wet. Water was getting in Melody's ballet slippers.

"Oh," Faye commented. "It's so pretty. I could stay here forever."

"Waterfall…" Percy mumbled. As usual, he was taking notes. "Water is commonly found in underground caverns. It is the cause of things such as erosion, stalagmites and stalactites."

"Stala-what?" Brayden asked, staring at Percy.

"Stalagmites and stalactites," Percy answered speedily. "Limestone is the chief form of calcium carbonate rock, which is dissolved by water that contains carbon dioxide, forming a calcium bicarbonate solution in underground caverns. If stalactites – the ceiling formations – grow long enough to connect with stalagmites on the floor, they form a column." The author totally didn't copy that from Wikipedia or anything. (Don't copy right claim me plz)

Brayden stared at Percy like he spoke a different language. Melody sighed.

"When water flows down through the ground and into a cave, it dissolves a mineral called calcite - a major building block of limestone - and carries it through cracks in the ceiling. The dripping water leaves behind traces of calcite, which slowly builds up on the ceiling until a stalactite takes shape, hanging down like an icicle," she explained. She spent way too much time with Percy. "Water from the end of the stalactite leaves more calcite in a pile on the cave floor, and pretty soon a cone-like stalagmite forms." She shook her head. These things were hard to explain. And yes, the author totally didn't copy that from the internet too.

"Ohhhh," Brayden said, nodding. He frowned. "Which one is the stalac… stalac… stalac thingy again?"

"The one that's on the ceiling," Melody sighed. "And it's 'stalactite'. Sta-lac-tite."

"THIS IS SO CONFUSING!" Brayden yelled. Melody groaned. Brayden could be frustrating.

"Hey guys, Sans is up here!" Cody chirped. He, Clover and the genderless kid were ahead. They were in a little area. There was a sentry station which Sans was running. A waterfall was on the ground. A funny-looking blue flower was by the wall, a monster standing beside it.

"An echo flower." Percy observed the flower. Cody, Faye, Percy and Clover went to speak to Sans. Melody found the genderless kid hanging with Brayden. They were writing 'stalagmites and stalactites' and drawing pictures of said things on the ground with their stick.

"Ohh," Brayden observed the diagram. "So… stalactites are the ones on the ceiling and stalagmites are the ones on the ground?" The genderless kid nodded. "YEAH! THAT'S THE STUFF!" That was funny. Brayden was glaring a lot at that kid yesterday. Now they seemed to be good old friends. Melody understood why Brayden would be jealous of them. Even she was a little envious of them. They were very talented. But now he was acting… different. She'd have to ask.

After the other four were done talking to Sans, the group continued. They found another box (still full of notes and spider donuts), then a rushing waterfall on their path. Rocks were flowing down the waterfall.

"It's based on timing," Percy observed the rocks. "And, well, simply, not getting hit." The genderless kid jumped into the water. Brayden jumped in after them, narrowly avoiding a rock.

"Brayden! Be careful!" Melody yelled, also climbing in. She cringed at all the water drenching her tutu.

"WHOO!" Brayden yelled. He splashed Melody with some water.

"OH COME ON!" Melody yelled. "Now my hair's all wet!" Brayden splashed some of the others as well. Percy ran away, trying to avoid that nonsense.

"You'll pay for that, pardner." Clover growled. She splashed some water back at Brayden.

"Um, guys, we're meant to be avoiding the rocks." Cody spoke up. Brayden almost got hit again. The genderless kid came back and dragged everyone along with them. They arrived on the other side of the waterfall.

"Hey, we should call Papyrus," Cody suggested. He looked shy. "I mean, if you guys want to. I just think it would be nice talking to him."

"You can, I'm not." Melody said. She walked away from Cody, Faye and anyone else who wanted to call Papyrus. Believe it or not, the genderless kid wasn't interested. And they were the one who flirted with Papyrus. Melody stood next to them.

"You and Brayden are getting on well," she told them. "He was jealous of you yesterday. What'd you do to…?" They non-verbally said something. "Oh, that's very cute." She frowned. "You know, you're very dangerous. My parents would never let me be friends with someone like you. But you're a great dancer. Really, you'll have to show me some of those techniques." The genderless kid shrugged.

"Yo!" the monster kid from Snowdin approached them. "Are you sneaking out to see her, too? Awesome, right?! I wanna be just like her when I grow up…"

"Who?" Melody asked.

"Undyne, duh!" Monster Kid answered, laughing.

"I don't know anything about her," Melody replied, raising her brow. "Apart from that she's in the Royal Guard."

"Wow, you're really missing out!" Monster Kid laughed. "Also, please don't tell my parents I'm here."

"My parents!" Melody exclaimed. "Oh, they'll be so worried about all of us." She almost started crying. She really missed her parents, even though they were art-obsessed. And ever so slightly neglectful.

"He didn't pick up…" Cody said, looking disappointed. Clover patted his shoulder.

"We'll call him later." she told him. Monster Kid approached the other kids and asked them about Undyne.

"She sounds so COOL!" Brayden yelled.

"I kinda wanna meet her myself." Clover agreed. The kids went forward again. They came to a spacious area with a patch of seagrass. The children were all covered in shadows. They looked kind of scary.

"What's the deal with-" Clover was interrupted by the genderless kid. They led everyone into the seagrass and put a finger to their lips. They looked very serious. To the north of the seagrass was a monster wearing heavy, silver armour. A flock of red hair was coming out of her helm. She wasn't facing the kids. Papyrus, covered in shadows and looking nervous, approached the armoured monster.

"It's Papyrus!" Cody whispered. The genderless kid shushed him.

"H… HI UNDYNE!" Papyrus greeted, staring at the armoured monster. "I'M HERE WITH MY DAILY REPORT…"

"So that's Undyne." Clover observed curiously.

"She's wearing a lot of armour," Melody added. "That'd be hard to walk around in, eugh." The genderless kid shushed Clover and Melody.

"She smells like fish! Eww!" Brayden commented, looking disgusted. The genderless kid shushed him too.

"UHH… REGARDING THOSE HUMANS I CALLED YOU ABOUT EARLIER…" Papyrus continued. Undyne faced him. "... HUH? DID I FIGHT THEM?" He paused.

"Poor Papyrus." Cody whispered. He stared at the genderless kid. "I know, I'm sorry…"

"What type of monster is she?" Percy asked. The genderless kid looked frustrated. Melody could relate. Annoying people were annoying.

"Y-YES! OF COURSE I DID!" Papyrus replied, trying to look confident. "I FOUGHT THEM VALIANTLY!" Undyne asked him something else. "... WHAT? DID I CAPTURE THEM? I TRIED VERY HARD, UNDYNE, BUT IN THE END…" He looked both anxious and upset. "I FAILED." Undyne stared at him. "WHAT? YOU'RE GOING TO TAKE THE HUMANS' SOULS YOURSELF…"

"Oh no, that doesn't fly." Clover growled. The genderless kid held her back.

"Yeah!" Brayden agreed. "Stupid smelly fish lady! You won't get past ME!" The genderless kid covered his mouth.

"BUT UNDYNE, YOU DON'T H-HAVE TO DESTROY THEM!" Papyrus pleaded. He approached Undyne. "YOU SEE… YOU SEE…" She stared at him. He took a few steps back. "I UNDERSTAND. I'LL HELP YOU IN ANY WAY I CAN." He left. Undyne stood there dauntingly.

"YOU WANNA GO, FISH-BREATH!?" Brayden leaped out of the seagrass. The genderless kid pulled him back in. Melody glared at him. Undyne pulled out a blue spear. She looked left and right, yet still glaring at the children.

"Don't take one more step." Clover warned. She held up her pistol.

"YEAH! OR YOUR, ER, SCALES WILL MEET MY FISTS!" Brayden yelled, making those fist gestures. Undyne's spear vaporised. She walked backwards, disappearing into the darkness. "YEAH, RUN COWARD!"

"You are so annoying." Melody told Brayden, giving him a look. The genderless kid gestured for the others to follow them out of the seagrass. They did so.

"... and that's why she's so cool!" Monster Kid was walking alongside Faye. Apparently she'd found the monster child hiding in the seagrass and started talking to them. Monster Kid gazed at the other kids. "Yo… did you guys see the way she was staring at you all…? That… was AWESOME! I'm SOO jealous! Wow, it almost looked like she was going to attack you, ha ha."

"I think she was, pardner." Clover told Monster Kid.

"Why would she attack random kids?" Monster Kid asked. They laughed. "She'd never hurt an innocent person. C'mon! Let's go watch her beat up some bad guys!" They ran off, but fell over and landed flat on their face.

"Are you okay?" Cody asked, staring at them with concern.

"I'm okay!" Monster Kid responded, getting up and racing off. Melody thought they were funny a child, sort of like the genderless one.

The kids arrived at the next area. There was a rushing river that was in the way. The kids had to use pretty flowers called Bridge Seeds to help them out.

"When they align in the water, they will sprout." Percy read a sign on the wall, taking notes. The genderless kid walked over to the flowers. They put one on their head (their hands were too small to carry something that big) and put it in the water.

"I'll help!" Cody cheered, racing over to them. His sister and Brayden pitched in too. Melody sighed. She gazed at Percy, who gazed back. Faye was sitting on the ground. She was observing the crystals in the wall.

"Isn't this place so pretty?" Faye asked, fascinated.

"It's much more similar to a cavern than Snowdin." Percy commented. He was observing his notes.

"Oh, Percy," Melody stared at him. "You really should play with us a little more. I know you don't like it, but, well… no one wants you to miss out."

"I like missing out." Percy replied, sounding emotionless. "Also, Melody, I saw this book in the Snowdin Library you may like." He handed her a book about the art of monsters. "It's all about monster entertainment."

"Wow," Melody replied. She observed the book. It looked pretty good. That was her and Percy's friendship. They were both serious and they shared some common interests. Percy wasn't caught up in his emotions. Melody respected that. And most of the time, they tolerated each other more than anyone else. Best friends forever.

"BRING IT ON!" Brayden yelled from ahead. Melody, Percy and Faye ran over to the other four. They were in battle with a monster named Aaron - a muscular seahorse (literally). I mean, a horse with abs and a mermaid tail. Brayden and Aaron were having a flexing contest. The genderless kid was flexing too.

"Flexing contest?" Aaron asked, sounding arrogant. "OK, flex more ;)"

"I'LL FLEX SO HARD YOU WON'T EVEN KNOW WHAT FLEX MEANS!" Brayden yelled.

"What's that supposed to mean?" Melody asked, staring at him. She gave him that mom-stare with her blue eyes. Oh, yes, she had deep blue eyes. Some people said they were intimidating, some said they were pretty, others said they were weird. Her dad had the blue eyes too. To him, they were striking. He once said, 'a sense of integrity'. Integrity. That was Melody's soul trait. In her opinion, it fitted perfectly. Even if she had to ask Percy what integrity meant.

"I DUNNO, IS HE SCARED YET!?" Brayden replied. Melody face-palmed. Aaron attacked the kids with his biceps, which sounds weird. But he did. The genderless kid, as usual, was protecting everybody. They and Brayden flexed at Aaron again.

"Nice!" Aaron complimented. "I won't lose, tho ;)" Again, he attacked the children with his biceps.

"It's so sweaty." Melody complained. Aaron was getting his perspiration everywhere. It was pretty gross. Brayden and the genderless kid flexed with him one last time. Finally, the battle was over. Melody was very relieved. That battle was too sweaty.

Ahead was another Bridge Seed puzzle. The bridge seeds were on a patch of land in between two lakes. One lake had the path where the kids could continue. But the genderless kid didn't go there. They went to the lake at the bottom, which led somewhere else. The kids copied them. They walked across the Bridge Seeds, coming to a small room with a park bench. Next to it was an echo flower.

"What's that, pardner?" Clover asked. The kids surrounded the genderless kid. They were looking under the park bench. They found an Abandoned Quiche.

"A quiche!" Cody observed.

"Eww! That's probably been under there for ages!" Melody scoffed, clearly repulsed.

"Poor quiche, someone left it here all alone…" Faye said sadly.

"It appears to be a psychologically-damaged spinach egg pie." Percy said, checking the quiche out.

"Can I have it?" Brayden asked, eagerly staring at the quiche.

"Brayden no!" Melody exclaimed. She didn't want him to eat old food. The genderless kid gave her a hey, it's okay, look. They'd been right before. Melody sighed. She knew she could trust them.

"I think it needs therapy…" Faye commented.

"It's food, Faye." Melody said, staring at Faye.

"I know," Faye replied. She sounded serious. "Whoever left it here just wasn't ready for the responsibility." The kids left after that. They returned to the main area. Percy observed the flowers.

"Oh," he said. "I know how to solve this." The genderless kid was ahead of him. "Oh. They do too." He looked almost disappointed. Melody patted his shoulder. She knew puzzles were one of the only things he enjoyed doing (aside from watching and reading stuff). As usual, Cody, Clover and Brayden helped out. The kids crossed the lake using the Bridge Seeds. There was a wooden entrance continuing the path. Suddenly, the kids got a phone call. Percy put the phone on speaker and held it in the air.

"Toriel?" Faye asked hopefully.

"HELLO! THIS IS PAPYRUS!" Papyrus' voice rang out. Melody groaned. Faye looked slightly disappointed.

"Hi, Papyrus!" Cody greeted brightly.

"How'd you get this number, Papyrus?" Clover asked. "I don't think we ever gave your our number."

"HOW DID I GET THIS NUMBER…?" Papyrus mused. He sounded cheerful. "I JUST DIALED EVERY NUMBER SEQUENTIALLY UNTIL I GOT YOURS! NYEH HEH HEH HEH!"

"Makes sense." Clover said, shrugging.

"Hey, Pap," Brayden spoke up. "We saw you talkin' to UNDYNE! SHE SMELLS LIKE FISH! ALSO, WHAT WAS THAT ALL ABOUT!? ARE YOU OUT TO KILL US?"

"He's got a point, Papyrus," Melody agreed. She was now pitching in on the phone call. "What was that all about?"

"YOU SAW THAT!?" Papyrus asked. He sounded embarrassed. "HOW EMBARRASSING! I AM SO SORRY YOU HUMANS HAD TO WITNESS THAT! THAT WAS NOT MY GREATEST MOMENT. NO, I AM NOT OUT TO KILL YOU. YOU ARE MY FRIENDS! BUT MY BOSS, UNDYNE…" He faltered. He changed the subject. "ERM… WHAT ARE YOU HUMANS WEARING? I'M… ASKING FOR A FRIEND."

"Undyne?" Clover asked suspiciously. "What's goin' on, Papyrus?"

"ERR…" Papyrus sounded anxious. Melody raised her brow. Although she wasn't the biggest fan of Papyrus and Sans, she didn't hate them. And she almost felt concerned for Papyrus. "I… I'M SORRY. I DON'T THINK I CAN TELL YOU." The genderless kid took the phone. Their brown hair was covering their face. They were turned away from the others. "OH? IS THIS THE RED HUMAN…? HELLO! … AH, OKAY…. YES, I SEE. THANK YOU VERY MUCH!"

The kids stared at each other. That red kid was so weird.

"HAVE A WONDERFUL DAY!" Papyrus hung up. The red kid gave the phone back to Percy.

"Okay, you can talk to people on the phone without talking?!" Brayden asked, staring at the genderless kid. He looked freaked out. "HOW DOES THAT WORK!?" The genderless kid shrugged. They continued walking.

"That kid just gets weirder and weirder…" Clover commented, biting her lip.

"There's something off about all of this," Percy said, looking over his notes. "Them. Us. Something's not right."

"What's not right, Perce?" Brayden asked, staring at Percy.

"Yes, Percy," Melody said, looking at Percy. Somehow she agreed with him. "What's not right?"

Percy hesitated. Everyone was looking at him. "I don't know. I… I don't know if I can explain…" He turned away. He was shivering. Melody frowned. This was when Percy couldn't take it anymore. Melody had been there when he had been overwhelmed once. It wasn't pretty.

"That's enough, everyone," she said, walking over to her best friend. "We'd better go on."

The next area was a stretched out cavern full of echo flowers, shimmering, blue roofs and a telescope. The genderless kid was waiting for the others.

"Wow…" Faye looked starstruck. "It's so pretty." Melody couldn't say she was wrong.

"A long time ago, monsters would whisper their wishes to the stars in the sky," an echo flower whispered. "If you hoped with all your heart, your wish would come true. Now, all we have are these sparkling stones on the ceiling…"

"Aww..." Cody said, almost bursting into tears.

"Stars are flaming balls of gas," Percy commented. "How could they make someone's wish come true?"

"Maybe you just have to 'believe', Percy," Melody replied. She didn't believe in magic either, but she did believe in hope. Percy didn't reply.

"Thousands of people wishing together can't be wrong!" another flower exclaimed. "The king will prove that. And the Fallen Angel…" The Fallen Angel. The one the bunny lady in Snowdin talked about. Melody remembered. Some human had fell down here long ago. They died heroically in some battle with other humans, but before they died, they promised they would rise again and destroy the barrier. Melody wondered if she would see them.

Suddenly, the children encountered Woshua. It was a small, funny looking monster that was full of water. It looked like a cup. It had one circle for a head, two clawed feet and a little bird swimming in its water. Woshua shuffles up. This humble germophobe seeks to cleanse the whole world.

"I'd like to be cleaned." Faye said quietly.

"Yes, I haven't washed for ages," Melody agreed. She snorted. "How irresponsible!"

"Green means clean." Woshua said. Bubbles of soap flew towards the kids. The genderless kid was pointing at the green ones, but pointing away from the white ones. One white one flew towards Melody. The genderless kid shoved her out of the way.

"Thank you," she told them. "You are so very good at this. How did you…?" They were racing off to protect other kids. Melody sighed. She reached out and touched a green bubble. Immediately, a warm, friendly sensation filled her body. Her HP was full again. Soon, the attack was over. The genderless kid spared Woshua. The battle concluded. After that, they were checking out a telescope. Everyone else joined in.

"Check wall." Percy read. Brayden ran over to the wall.

"DO SOMETHING!" he yelled at the wall. The genderless kid came over. A doorway opened. "YEAH THAT'S MORE LIKE IT!" He raced in.

"Oh, Brayden!" Melody complained. She went in after him. The next area was on a bridge. Dark water was flowing around underneath it. Water sausages were sitting in the water. Ancient writing was on the walls. Percy was obviously interested.

"It's about the war," he said. "'The War of Humans and Monsters'." He read another sign on the wall. "Why did the humans attack? Indeed, it seemed that they had nothing to fear. Humans are unbelievably strong. It would take the SOUL of nearly every monster… just to equal the power of a single human SOUL."

"Wow!" Cody exclaimed.

"What were humans afraid of?" Clover asked, looking interested.

"WHO CARES!? HISTORY IS BOOORIINGG!" Brayden whined. He wanted to race off. The genderless kid didn't look too interested either. Melody glared at Brayden.

Percy continued, "But humans have one weakness. Ironically, it is the strength of their SOUL. Its power allows it to persist outside the human body, even after death."

"So that's where ghost stories come from…" Faye remarked.

"But why?" Clover asked. "Why did we do that to monsters?"

"If a monster defeats a human, they can take its SOUL," Percy read. "A monster with a human SOUL… A horrible beast with unfathomable power." He observed his notes. "It comes to one conclusion. The humans were afraid. They were afraid of the monsters' power."

"So," Melody looked thoughtful. "If one of us was killed by a monster, they could take our SOUL?"

"Yes," Percy replied. The genderless kid looked a bit uncomfortable.

"NO ONE'S TAKING MY SOUL!" Brayden yelled. The genderless kid looked even more uncomfortable.

"That's not gonna happen." Clover agreed, clutching her pistol. The genderless kid hid their face. Melody wondered if they were okay. She walked over to them. They just shrugged at her.

At the end of the bridge was a platform. It could ride across the water to the other side. However, it could only fit one child at a time. Everyone had to take turns getting across. They arrived on another bridge. Shadows crawled down their bodies. The water sausages looked a little creepy. Stone pillars were on one side, concealing something.

"I've got a bad feeling about this…" Cody commented. The feeling in the air was eerie.

"COME OUT AND FIGHT ME, ANYONE OUT THERE!" Brayden yelled, looking around.

"This is so stupid." Melody commented. All of this was. Fighting. War. Falling underground. Melody just wanted to go home. She never asked to die. Suddenly, a bright spear came down from the sky. It would've impaled her if the genderless kid hadn't pulled her back.

"Undyne." Percy breathed emotionlessly. The armour-wearing fish lady appeared, glowing spears beside her helm. Lots of them. The kids stared at each other.

This wasn't going to end well. The genderless kid seemed to know what to do already. The others weren't so confident.

Melody ducked, dodging many of those spears. Somehow. Adrenaline made her heart race. She didn't feel good. She raced forward, gazing at her friends. Clover had a spear in her shoulder. It looked like she was trying to defend Cody. Brayden also had a spear in his shoulder. He was growling.

"We need to get around that bend," Percy said, standing nearby Melody. "We can make it." Just as he said that, Undyne threw more spears. One landed in Percy's arm. His glasses slipped to the edge of his nose. Melody got a glimpse of his purple eyes.

"P… Percy!" she exclaimed. She glared at Undyne. No one hurt her best friend. "You… you monster!"

Undyne was throwing more spears. One almost hit Faye. The genderless kid turned around. They pulled everyone together and defended them all at once. They were getting a lot of spears in their body, but somehow they didn't look pained, even though their body was twitching. Their sweater was turning red.

"You really are brave, aren't you?" Melody asked, trying to wipe all the blood off Percy's sweater. She couldn't stop shaking. Everyone was getting hurt. The kids ran a little more, approaching some sea grass. The genderless kid could barely move. They fell over, their body twitching. They were covered in glowing spears. It was a horrific sight.

"Oh no…" Cody looked horrified. He helped the genderless kid stand up. Brayden shook his fist at Undyne. Melody observed the genderless kid. They were still alive, like they were refusing death.

"Melody…" Percy spoke up. He was allowing her to help him stand, which was a rare sight. She led him into the sea grass. It concealed their bodies. Faye was in there too, shivering. Clover was clutching her pistol. Cody, Brayden and the genderless kid joined them. Brayden went over to Faye and stood protectively beside her.

"Don't give up, Percy…" Melody mumbled, smiling at her best friend. Percy shook his head. He was anxious, strange and geeky, but Melody knew he was very determined. He never gave up. Spears flew overhead. The genderless kid was covered in blood. Yet, somehow, they didn't look bothered at all. They didn't break a sweat. They were very determined too. Melody felt her eyes go watery. She hated this so much.

Suddenly, footsteps boomed behind them. Undyne was approaching. Her red hair was sticking up. Her armour shoved past the seagrass. Melody felt angry and upset. Why did everyone have to be so violent? There was no need to fight. Unless it was the right thing to do, of course. And right now, it wasn't that at all. Melody sniffled, supporting Percy. The genderless kid, somehow, encouraged everyone to stay quiet. Melody had no idea how they hadn't dropped dead.

Melody felt something pulling her upwards. She looked up in horror and saw Undyne, her eyes glowing. She was so dead.