Sans is a MONSTER and not a HUMAN, so he doesn't follow HUMAN biology like a HUMAN skeleton. Same with Gaster and Papyrus.      

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"Fuck this guy!" Chara growled, as she honestly felt out of breath, chasing after this stupid prick that Frisk had wanted to kill for her mission. What made it even more of a pain in the ass is that he wasn't even alone anymore, and had two monsters who were helping him. Well-- One now, seeing as Chara had just had enough of the shit and decided to shoot one of them directly in the head. Thankfully, they hadn't saw it coming. When Chara had agreed to come on this mission with Sans and Frisk, alongside Asriel, she didn't think it would involve so much running. Most missions were pretty intense, but she hadn't been on one so intense in so long that it was somewhat exhausting. 

Since Frisk had begun to recover from her injuries, she had wanted to track down the bastard that had almost killed her, but of course this time there was no way in hell that Sans was going to let her go alone. Even if she had said it was her fight, there was just no way. It had took some arguing with her on the subject, but thankfully, she eventually agreed. He had to clarify, it wasn't at all that he thought she couldn't look after herself, because she quite clearly could. However, he just didn't want to risk it. 

"You're just delaying your death this way you know!" Chara yelled after the human murderer who had jumped across to the next building, with his newly found monster friend following after him. Asriel could only exhale, while even Sans and Frisk stood, looking pretty fed up. What was with this guy and his love for doing parkour? But Chara was right, the more he ran the longer he was delaying the inevitable. The man smirked. 

"I think the only people's deaths we are delaying are yours." He replied, before the monster next to him readied an attack, seeming ready to throw it at them. Asriel had narrowed his eyes, ready to block the attack, while Sans was ready to protect Frisk at a moment's notice. However, instead of throwing the attack directly at them, it was thrown at their feet, at the edge of the building they were standing on, causing the small area they were standing on to break off. Luckily, Chara backed away just in time to stop herself from falling, but she could only scream to Asriel as she saw him, Sans and Frisk go and fall off the end of the building. 

"shit! asriel, grab my hand!" Sans had yelled, as he, Frisk and the goat monster were all falling through the air, ready to plummet to their deaths. He was already holding onto Frisk, but he needed the goat to grab his hand, so he could teleport them all to the ground, safely. No, he didn't like using magic because it tired him out easily, and could cause greater harm if he used it too much. But if he didn't do anything right now, the three of them would die. This guy was tricky, very tricky. As he had hoped, the goat went to put his hand within the skeleton's and in that moment, they found themselves falling, only to be upon the ground, safely in a single flash. It was clear that Sans was already tired, especially from all the running they had already been doing. 

"Uh, guys!" Frisk yelled out, looking up above towards the guy, just as Asriel and Sans looked ready to celebrate the fact that they weren't dead. What they had forgotten to recall was the fact that there was some more falling debris coming from the building, ready to land right on top of them. Chances are, they wouldn't be able to move out of the way quick enough. With that thought in mind, the skeleton quickly went to lift his arms as his bright blue glowing eye lit up within his eyesocket, and using his magic, he managed to stop it. Of course, not without some grunting and effort. However, he couldn't hold it for long, not very long at all. The debris was pretty heavy, and that only put more of a strain on him for trying to hold it. 

Crack. And just like that, the magic that was holding the falling debris was gone, and the rest was sort of a blur. Sans had gone to the ground on one knee, using one hand to hold himself up, while the other was gripping a hold of his shirt, around his chest. It was his soul, he had managed to crack it a little more once again. He could already hear the panic in Frisk's voice, but he was okay... At least, okay as he could be. Then there was Asriel saying they should seriously move, and the sound of Chara yelling something, but after that, it was just dark.

"ASRIEL!" That was what Chara had screamed once again, right before she saw the group of three get seemingly crushed by the debris. She couldn't believe it. There was no way... It was all just so fast, so unexpected, that there was absolutely no single way that those three were dead. There was just... No way. Chara stood on that building in disbelief, all while she heard that monster and the human cackling, as instead of running, they had stood around to watch the "show". Growling under her breath, Chara rose her gun and fired the trigger, hitting yet another monster, right in the middle of its forehead, causing it to fade into dust along with its meaningless existence. No one should mess with a girl who had excellent aim like she did. 

"GET FUCKING BACK HERE!" Chara yelled, as she saw the guy trying to run away. She knew Frisk had wanted to take this fucker down, but if Frisk was really gone, then she would happily continue her wish on for her. She wasn't letting this fucker get away, especially when he may just have killed the girl she saw as a sister, Sans who was... Admittedly still sometimes a prick, but he was a better friend to have ever since he had Frisk and... Asriel. Asriel was just... She would never forgive anyone who took him away from her. So, as he tried to run, she aimed her gun once more, managing a clear shot to one of the back of his legs. As she fired, it felt satisfying to hear him scream and fall over.

Not wasting much time, she took several steps back, only to start running forward, and she jumped to the next building - the one he was currently on. She could see him trying to clamber back up, like he still had some kind of chance. Similar to the way a Zebra would try to escape from a Lion despite being badly injured, there was just no chance. Mercilessly, Chara took another shot to his other leg, causing him to go falling over all over again. "You fucking bitch!" He had growled in pain, but Chara didn't care that this man was hurting. In fact...

A wide smirk fell over her face as she towered over him. If you had the imagination for it, you could probably imagine her normally calm, pupils, burning like raging flames, as if she was staring right through the soul of this disgusting man. He deserved everything that came to him, and that's why before instantly taking him out, she decided to shoot him in both his arms, causing him more agony in the process. "Does that feel good? Does it feel fucking good?!" Chara laughed, (which no doubt had an extremely eerie feel to it). "I hope you burn in hell, you worthless, pathetic, disgusting piece of shit!" She screamed at him, only to keep shooting him repeatedly, at least until she had used every bullet in the gun. By that time, he was already dead. In fact, he had probably died after the first couple of shots, but she had been too angry and kept up in the moment to notice. 

Slowly, she breathed in, and then out... Just trying to calm herself down, before beginning to take her leave, as quick as possible. She had to get down to the ground, and see if the others were okay. They had to be! There was no way that they were just suddenly dead like that. Yeah, sometimes people did die on missions but... Not them! Never Frisk, never Sans, never Asriel! By the time she had gotten to the ground, it seemed some random strangers had started to crowd around the scene, making it impossible for her to see what was going on. 

"Move out of the way please, excuse me!" Chara yelled, pushing people aside to get to the front, so she could see if they were okay. Please, be okay... They had to be, despite her brain making her imagine the worst case scenario. Her brain imagined up the image of seeing their blood splattered across the concrete from being crushed by the large bits of debris. She imagined seeing Frisk's hand stick out from beneath all that destruction, with bits of dust laying with her. Just the thought was enough to make her sick, as she finally pushed herself to the front. And what she saw, she could not believe.

Despite the bits of debris being quite big, the rocks were being lifted up by the tallest monster in the group, that of course being Asriel. Both Sans and Frisk looked like they were filled with uttermost relief, as they crawled out from under the mess, and Asriel was able to free himself from all that chaos as well. They were all looking slightly tattered up and dusty, (only due to the broken pieces of building), but apart from that, they were perfectly fine. Sans did look a little tuckered out, but that was about it. 

"Asriel!" Chara practically raced to the goat the moment she saw him and hugged him tight, only to begin crying as she was just so glad that he was okay. She didn't know what she would have done if she had lost him. After all, Asriel was the person who she was closest to out of anyone she knew. He just... He meant a lot to her, that's all. 

"don't ask if we're okay then." Sans jokingly said, only to chuckle a little when Chara told him to shut up, while she continued to hug Asriel and he began to hug her in return, seeming to reassure the girl that he was okay, that he wasn't hurt. 

"Are you okay...? I was worried you were going to hurt yourself again after using your magic." Frisk said worriedly to Sans, while the monster and the human were busy hugging it out. The group were very clearly trying their best to ignore the crowd of people that were just standing, staring at them in confusion. But to their luck, just as the couple were having this conversation, none other than Undyne had appeared to show up, seeming to usher people away from the scene. 

"i'm fine. i mean... i might have cracked my soul a little again." He said, but at Frisk's alarmed look, he continued. "really, it's not that bad. or at least, as bad as it was that last time. i'm still conscious, aren't i? as long as i take the time to rest from it, i'll be fine." Sans reassured her with a small smile, and he could only chuckle a little more when she decided to tightly hug him from the side. He put an arm around her, holding her close. "do ya feel satisfied, now that that guy is gone?" 

"...Yeah. Yeah, I think so." Frisk smiled, feeling like maybe now a bit of a weight had been lifted off of her shoulders. And hearing that made Sans feel more relaxed too, because she had said that once that guy was dead, she had promised to quit. He was hoping she would keep that promise, and he found it difficult not to beam when she spoke up. "Well, I guess I better keep my end of the bargain... Today is the last time you'll find me going on a mission. Especially when we could have almost died, again." Frisk guiltily grinned, seeing as today, she could have almost taken two people with her. She sighed. Part of her didn't want to quit... Part of her wanted to stay as a member of the Mafia, because it felt like it was just a part of her now... But she had no choice. She promised. 

"So, I'll finally quit."