FireCacodemon: Welcome to my DtB/Undertale Crossover. Disclaimer below but I hope you enjoy this one-shot.

Judgement Hall Meeting

A Darker Than Black & Undertale Cross-over Fan-Fiction

Written by FireCacodemon

Disclaimer: Darker Than Black belongs to Tensai Okamura

Undertale belongs to Toby Fox

Summary: Sans confronts Hei in the Judgement Hall. One-shot!

Sans wasn't sure what had just happened. He didn't feel Chara possessing the boy's body but something else. Something just as bad as Chara, something who killed without mercy and without compassion...yet it spared his brother, Papyrus and then killed everything else it found. Actively seeking out every little monster who roamed in the Underground yet it spared Papyrus. Why would someone kill everything but leave two skeletal brothers alone? Sans could have come up with lots of different theories about what was going on but nothing gave him a satisfying answer. He watched as the child walked through the underground swinging that burnt pan around, gaining more EXP and occasionally, gaining another LOVE. The monsters feared him as he approached them but stood their ground and tried to defeat him...they fell. Sans couldn't even tell what was going through the child's mind, those midnight orbs didn't hold anything, the door to his soul was closed and no trace of emotions were found. The child didn't care much about the puzzles or even the whoopee cushion hand trick that Sans himself had pulled on him. Sans noticed back then that even though he passed the 'puzzle' word search on the ground he went back and finished it when Papyrus had left.

*you liked the word search yet you're killing every monster you cross? where's the fun in that?

More and more monsters fell to the burnt pan as the child headed towards the Core. Mettaton was going to face the human and he was going to fall, Sans didn't need time to tell him that. Yet he couldn't tear himself away from watching the child as he continued down the dark path of murder. His hands were in his pockets and his hood was up yet the child had failed to detect his presence. He should have been grateful that he had spared Papyrus...but he left him waiting instead of going back to hang out. Sans approved of this choice but he hated to see that Papyrus was waiting for him to return just so they could hang out. His 'lessons' had worked well on the child...or did he know what was going to happen if he continued down the path? Sans had warned them before that they were going to have a bad time. Is that why they had decided to spare Papyrus? No, real sinners wouldn't even consider sparing anyone or anything if they got in the way. Watching the child enter the core, Sans decided that he should just get ready for them to arrive at the judgement hall. He would get his answers that way.

Darker Than Black - Judgement Hall Meeting - Undertale

Hei watched as Flowey shook with a scared expression on his face. He had just realised his mistake and he just understood the mistake he had just made. If what he said was true, then neither of them would hesitate to kill each other. He was right, he had spared Papyrus and he did enjoy his puzzles but he knew that Flowey was following him he gave up trying to escape from the persistent flower in Waterfall. Playing the piano located in Waterfall reminded him of someone who he once knew. A female doll named Yin but...now he was stuck in this loop. This was just another time line he was making to then just reset and ignore. Like Flowey had said before, this world could get boring just like every world can. This time, he was only keeping Sans and Papyrus alive and hopefully that'll give him the power he needed to move on from this loop. No one else mattered to him but the two skeletons in this time line. Hei wanted to win every game but also to lose every game. He still had a way to go before he ended up like Flowey, wanting to destroy this world over and over and over again. He felt his human side hovering behind him, he wanted Sans and Papyrus alive and Hei was happy to keep the two alive. He had yet to kill EVERYONE. He had yet to create genocide. He had yet to lose his human side for good...no...He'll come back every reset just like Flowey did. His LOVE and EXP were high, just like they had been in the last time line when he killed Papyrus and left Undyne alive. She naturally tried to kill him whenever she could but he was always quicker.

Hei walked into the judgement hall, having being judged countless times in the past by Sans. He was sure that Sans was different to the other monsters, he seemed to be aware of the timelines that Hei and two others had control over. Flowey had mentioned another person who had control over the time lines, a child named Frisk who had the chance to be possessed by a spirit named Chara. Flowey had stated himself at times that even he had power over the time lines...Frisk had replaced him and Hei had replaced Frisk. That was the way that this Underground worked? Someone with more power falls down here and the power to Save and Load jumped to the next powerful person. The power craved strong souls or someone who had the will or desire to manipulate timelines at will. Hei found another save point and just passed it, he didn't care about saving any more. He knew everyone's moves and what he needed to do in order to avoid taking a hit. He stocked up on food none the less and even Burgerpants was thrilled with how much gold he was spending on Legendary Heroes. Opening the box, he organised his inventory so that his food was easy to reach. Once organised, he headed down the golden corridor with the Underground symbol stain glass windows allowing golden light into the room.

*hey kid. been a while, huh?

"Sans." Hei said in his usual cold tone of voice. The smile on Sans' face never left, it remain stuck on his face as his world crumbled around him. Sans watched Hei before he shrugged.

*you've been very busy huh? actively seeking out monsters to kill, stuffing your face full of food for that never ending hunger. papyrus would sure love to keep you as a pet.

"Too bad that I'm not going to be anyone's pet. Please, judge me and get out of my way so I can finish this timeline," Hei said as he took a step forward.

*i can't let you do that. i do have some questions though, if you don't mind me asking of course.

"Doesn't matter what I think, you're going to ask them anyway, aren't you?" Sans let out a small chuckle.

*why did you keep papyrus alive...yet kill everyone who crossed your path? it just doesn't make sense to me.

"Why did I keep Papyrus alive?" Hei repeated Sans' question before he smiled. "Because...I didn't want to make him unhappy."

*him?

"Yes, he's watching me now. He requested that I keep you and Papyrus alive, everyone else can die." Sans digested this information. He could accept it and see that there's another personality in him much like Frisk was possessed by Chara and committed genocide...or he would write it off and call it a lie.

*what's he like? this other personality?

"He'll be like this Frisk person was once. Every monster would be spared and you'll have your 'happy ending'."

*why not let us have that?

"I want to win every game...I want to lose every game...I want to become more like Flowey, I want to be disconnected from the world...Both of us want to fade away. We don't have anything left...until we have something we want to live for...I'll consume timeline over timeline until I'm happy...when I'm happy, you can have your happy ending."

*happy ending huh? that's what you're after but don't know how to get. well, maybe i can't give you what you desire but what will fading away do to help get this 'happy ending' you're after? nothing. have you done a timeline when you're sparing everyone?

Hei shook his head.

*why haven't you done a timeline like that?

"I...don't...understand..." Hei started before his hands started to shake. Sans noticed the shaking and looked back up at Hei's face. For once, there was something swirling in those midnight orbs. Confusion. He really didn't understand mercy, did he? Maybe he didn't understand it because no one really showed it to him or was there something else going on?

*hey...how do you make a skeleton laugh?

Hei looked at Sans and tilted his head in confusion.

"How?"

*you tickle his funny bone.

Hei stood there unsure of how to react. Slowly his mouth started to form a smile and slowly, laughter came from him. It only took a few moments before Hei had lost control of his laugh, he couldn't stop laughing for some reason. Just because Sans had said a joke he found himself laughing his head off. Sans watched in a state of confusion. All he had said was one bad pun and it had this kid laughing so hard that he had started choking on the air around him.

*are you okay?

"Thank you, for making him laugh." Sans noticed the personality change quickly.

*heh, no problem kid. i don't normally ask this but...can you restart the timeline?

"I don't know if he'll be in control next time but we'll be back. Maybe next timeline, we'll work together both me and Hei." And with that, a RESET button formed under Li's hand. He smiled and pressed the button. The world around them both went dark and moved in reserve. Events passed them both quickly as it reached Snowdin, Sans felt himself being plucked out. His vision faded as he arrived back in his own bed with the self-sustaining vortex still spinning in his room. Another timeline had started. His memories had blank parts just like it always did but he did remember one thing. A human was going to come through the door of the ruins.

FireCacodemon: Well, that's it. Thank you for reading. Have a good day/night.