Hello readers. It is I, Em, here with a story. I figured this one would do better on this site than ao3. Especially with the nature of my ao3 stories compared to this one. If you enjoy seeing your favorite characters in triggering depressing situations, head on over to ao3 and look for mysterem. Now that I am done shamelessly promoting myself please enjoy this hastily written chapter. I will hopefully have another one out soon, but in the highly likely scenario that I don't, please be patient and I will get it to you whenever I can. Thank you, and enjoy!

I do not own Undertale or Harry Potter.

Edited 2/3/16

It had been one year since the battle of Hogwarts. The school was mostly rebuilt, and was opening its doors once again to students, including any previously seventh years who felt the desire to come back for a more thorough education, as eighth year students. This is why Harry, Hermione, and Ron found themselves sitting on the Hogwarts express, with varying emotions.

Hermione was excited for more learning, but worried about Harry.

Ron was looking forward to quidditch, but was worried about Harry.

Harry was just worried in general.

The last time he had been at Hogwarts, he had lost so many friends… He wasn't sure he was ready to go back to where it had all happened.

"Har-"Hermione was interrupted by a knock on the sliding door. She stood, opening it, and coming face to face with a child with their eyes squeezed shut, and a baggy sweater. The kid turned their head towards the empty seat next to Harry, before pointing at it, tilting their head to the side as if asking a question. "Er…Are you asking to sit there?" She asked. The kid nodded.

"Yeah, go ahead." Harry answered, scooting closer to the window. The kid sat, smiling faintly. The three older occupants shared a look, before Hermione opened her mouth to speak again.

"Hermione, don't." Harry sighed. "I've already told you, I'm fine."

"Harry, please. We're all just worried about you."

"You don't need to be. This year is going to be fine. Voldemort's gone, nothing bad will happen."

"I dunno, mate. You read the Prophet today?" Harry shook his head at Ron, who handed over the newspaper he had been skimming.

"No, I didn't have time."

"Well, say's here the barrier at Mt. Ebbott's been broken." Hermione gasped, but no one noticed the expression on the strange kid's face briefly change.

"Mt. Ebbott?" Harry asked.

"I read about it a few years back. Apparently there was a war between a certain group of monsters and humans. Several wizards banished them underground and sealed them in with a barrier. But if the barrier has been broken then…"

"The monsters can get out." Harry finished. Hermione nodded. "But what does that have to do with this year at Hogwarts?"

"It said a wizard kid broke the barrier. A kid who goes to Hogwarts."

"A Hogwarts student?" Hermione was shocked. "They'd have to be a very powerful witch or wizard to do that! Does it say their name? I'm sure we would've heard of them."

"No." Harry replied, quickly reading through the article. "It says the family preferred to keep that information private. But again I ask, how does this affect me?"

"Well…You know…" Ron started lamely. "It could mean trouble, and trouble usually follows you. Or at least, it finds you." Harry couldn't think of an argument. He knew his friend wasn't wrong. Trouble did find him. It was rare for things to be calm when Harry Potter was around.

He quickly changed the subject by pointing out the score of a quidditch match on the next page of the Prophet. Hermione just rolled her eyes as the boys talked excitedly about the upcoming school year's matches, and opened her book. Once again, the shorter child was left unnoticed, and stayed that way until after they had slipped out upon reaching the platform.

-Harry Potter and the Child of the Underground-

-By Myster Emm-

Frisk let out a deep breath after exiting the Hogwarts express. That had been too much, being around that conversation. They hadn't thought it would be so hard to hear about. But when they heard Mt. Ebott, all they could think about was watching their friends die... Feeling themself die...

But that was in the past, right? Yes. Yes it was in the past. They were home now. The monsters were fine. Everyone was...fine...

Except for the fact that they were about to start a their year at Hogwarts and they weren't prepared for that. When they made it out, they had gone home. They had spent the next year trying to readjust to life on the surface, and despite having only been in the Underground for a short amount of time, they still never truly felt the same when at home. They had requested a pie their first night home, but had been disappointed to taste apple. The golden flowers that bloomed in their mother's garden each spring had caused them to cry. Puns were always met with a sad smile that quickly turned to a frown. They felt sad often, now. Life with humans just wasn't the same. Even the arrival of their Hogwarts letter on their eleventh birthday didn't make them as happy as they had once thought it would. Their parents never seemed to notice, too busy celebrating with friends the downfall of the Dark Lord.

It was a year and a half after returning home, and just a few days before departing for Hogwarts that their mother had blabbed about them to some reporter. Their father had quickly paid the reporter off to keep their name quiet, but the damage was done. The Daily Prophet published a piece about a child breaking the barrier and potentially allowing monsters to join humans above ground.

They had thought that maybe no one would care, or that everyone would write it off as a hoax, but then that conversation on the train...

"Firs' years! Over 'ere!" Frisk jumped a bit as the loud, booming voice of Rubeus Hagrid pulled them out of their thoughts. They followed some other first years over to the boats, and were unimpressed by the ride across. In their opinion, the River Person had given a better ride.

The first years were lead into the Great Hall, which they had to admit was cool. Although the number of ghosts was worrisome (and they were surprised by the more human appearances, and lack of headphones). They had been so lost in their surroundings, they were startled when they heard their name called. The took a deep breath, and walked up to the stool, the hat being placed on their head.

"Well isn't this interesting?"

THE SOUND OF THE HAT'S VOICE IN YOUR HEAD FILLS YOU WITH DETERMINATION.