Remus closed the front door of his house and walked down the pavement, a box of brownies under his arm.

He was kind of nervous. I mean, it's not every day that a skeleton comes around your house to ask you to a house warming party. He looked up at the house he was walking towards. It had been on the market for months. People had looked around it but no one had bought it, given as it was so big and expensive. The only people who could afford it probably didn't want to live in a small town like that.

Remus went up to the door and knocked. A few moments later, the door was opened.

'hey, you came! i was getting worried you wouldn't turn up. i don't know how i would have explained that to paps,' Sans greeted. 'anyway, come on in, i'll introduce you to everyone.'

Sans lead Remus through the door and into the lounge. Sat on one of the sofas was a lizard woman wearing glasses and a lab coat and a goat man with a yellow beard who was wearing a knitted jumper that read 'Mr Dad Guy'. On the other sofa, there was a white ghost. Not like the ghosts at Hogwarts. This one had less detailed features compared to the ones Remus was familiar with. The final person in the room was a robot. It had pink and black metal plates, pink boots and had black hair, the fringe covering its right eye. It was posing on the sofa

'hey, guys, this is...' Sans paused. 'it just occurred to me that i never asked for your name.'

'Remus Lupin.'

'okay. guys, this is remus. remus, this is alphys, asgore, napstablook and...mettaton.'

Sans sneered the last name. Remus gathered that the small skeleton didn't really like the robot. The other four in the room said hello as Remus waved.

'alphys used to be the royal scientist in the underground, asgore's the king of monsters, napstablook's an up-coming dj and mettaton is...a metal-assed fucker.'

'Oh, Sans, I know you love me really,' Mettaton replied, winking. 'Everyone does.'

This reminded Remus of his friend from Hogwarts, Sirius Black, for some reason.

'i really don't,' Sans replied to the robot.

'Erm...Underground? Monsters?' Remus asked.

'man, i keep forgetting how little i told you when i met you,' Sans replied. 'basically, centuries ago, humans and monsters lived together on the surface. then, a war broke out between the two races. the humans won and forced monsters underground, sealing us there with a magic barrier. not long ago, a kid fell underground and broke the barrier, setting us free. now, we live here again. the kid acts as our ambassador to the humans and life's pretty sweet.'

'Woah...' Remus gasped. A single child saved an entire race from their underground prison?! Suddenly, being top of his class in most lessons at Hogwarts seemed really underwhelming.

'HOTTER!' a yell suddenly came from the kitchen. 'LET YOUR HOPES AND DREAMS TURN INTO BURNING FIRE!'

'I do not think that is the correct way to...'

'NGGGGAAAAAHHHHHH!'

'well, i think that's my queue to introduce you to the others as well as stop them from burning the house down,' Sans said, leading Remus into the kitchen.

The room was basically split down the middle. On one side, a goat woman was pulling a delicious looking and smelling pie from an oven. On the other side, a blue fish woman with red hair and another skeleton, who was a lot taller than Sans and had a red scarf and... cool? ...outfit, were stood by a stove, boiling a pan of spaghetti. They were over heating it way too much.

'HOTTTTTTTTEEEEEERRRR!' the fish woman yelled as the tall skeleton turned up the stove's heat even more. Suddenly, a blue aura surrounded the knob the tall skeleton was turning, and turned it back down to a lower heat.

'SANS!' the tall skeleton yelled. Remus turned to the smaller skeleton to see that his left eye socket was glowing blue with flecks of yellow.

'sorry, bro,' Sans said, blinking and turning his socket back to normal, 'but i'm not gonna let you burn the house down just after we bought it. anyway, guys, this is remus. remus, this is my brother, papyrus, undyne, the ex-head of the royal guard and toriel, the queen of monsters.'

'Ex-Queen,' Toriel corrected.

'HELLO, SECOND HUMAN! I, THE GREAT PAPYRUS, AM DELIGHTED TO MEET YOU!' Papyrus said. It seemed he had no such thing as an inside voice.

'It's nice to meet you to,' Remus said. The boisterous yet slightly narcissistic tone of the skeleton reminded Remus of his school friend, James Potter.

'hey, where's the kid?' Sans asked.

'She's out getting some spider doughnuts from Muffet's,' Undyne replied.

'Oh, Sans, that reminds me, could you go get Flowey?' Toriel asked.

'sure,' Sans replied and left the room, going upstairs.

'Um...I brought some brownies with me,' Remus said.

'Oh, really? Wonderful!' Toriel said. 'Did you make them yourself?'

'Yeah, I did, actually,' Remus replied.

'I can't wait to try them!' The goat then added, whispering. 'It will be nice to have something else edible tonight.'

Almost as if solidifying her statement, Undyne asked, 'Uh, Toriel? Where do we keep the fire extinguisher?'

'I think it's best you go back into the living room, child,' Toriel told Remus. 'It's probably much safer in there.'

Remus did so, taking a seat next to Alphys.

'So, Remus,' Mettaton said, resting his head on a hand, 'why not tell us a bit about yourself?'

'Well, uh, there's not much to say...' Remus replied, scratching the back of his head. 'I'm a nerd, I guess.'

'Really?' Alphys asked. 'Uh, d-do you like anime?'

'I do, actually,' Remus replied. 'Death Note's my favourite one. L's my favourite character.'

'I'm gonna stop you right there before Alphys starts her anime lecture,' Mettaton said. 'Tell us about your school, friends, family. Just...anything but anime.'

'Well, I go to, um, Hogwarts School for...gifted children. I'm the top of most of my classes. I have three really good friends there. James Potter, Sirius Black and Peter Pettigrew are their names. As for family, well...I had a twin sister.'

'What do you mean "had"?' Asgore asked.

'A month ago, she went missing and was presumed dead.'

'Oh...well, I'm sorry for your loss,' Asgore said.

'No, it's okay. I shouldn't have mentioned it...'

'Don't worry! This party's already crap as it is. Talking about death won't make much of a difference,' a new voice spoke.

Sans was walking down the stairs, a flower pot in his hands. The flower in the pot had six yellow petals and a face.

'Howdy!' it said. 'I'm Flowey! Flowey the- '

'fuckface,' Sans finished the flower's sentence.

'I'd shut up if I were you, Smiley Trashbag,' Flowey growled, 'unless you want a face full of friendliness pellets.'

'he's soulless, so, if he says anything shitty to you, don't take it personally,' Sans told Remus, placing the flower on the coffee table.

'Wait, he literally has no soul?' Remus asked.

'Yeah...I, uh, s-sorta made him. i-i was doing experiments on m-making souls persisting after death and I w-w-wondered what would happen if you gave something w-without a soul the will to live,' Alphys explained. 'He was the result.'

'Howdy! I'm Flowey, your first fuck up!' Flowey said, giggling.

'Don't listen to him, Alphys,' Mettaton reassured. 'Only someone amazing could make a robot so fabulous!'

'Th-thanks, I guess...' Alphys replied.

Suddenly, the front door opened and a girl stepped into the living room.

'Sorry, I'm late. The queue at Muffet's was really long,' she said.

Remus couldn't believe his eyes. It couldn't be...

Yet the shoulder length brown hair, blue jumper with purple stripes and seemingly closed eyes were all too familiar.

'remus, this is- '

'Frisk...' Remus interrupted Sans. 'You're alive... You're alive!'

He ran up to his twin and pulled her into a hug.

'I missed you so much! I just...I can't believe it!'

'Uh...' Frisk looked hesitant. 'You must have mistaken me for someone else. I... don't think I've ever met you.'

'...What?'

Thank you all so much for reading. I hope you enjoyed this chapter.

To HRTG1027: Thanks! I'm glad you're enjoying it.

To pandaxoom: Well, this is the kid who turns into a bloodthirsty beast once a month and sees all sorts of wacky creatures on a daily basis at Hogwarts. He's probably like, 'Yup, same shit as always.'

To Quartermass: I always like stories with dark beginnings. They really draw you in. I'm happy you enjoyed the chapter.

To CartrigeReality: Well, it's safe to say his reunion with Frisk didn't start the way he hoped... And, also, thank you! I've read quite a few Undertale/Harry Potter crossovers but didn't see many ideas like this so, when it came to me, I felt like I needed to share it. I hope you keep enjoying it.