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

-----------------------------------

Entering his office after being called into the room, it was no surprise that they found Gaster, sitting behind the desk, his chin rested on the back of his hands. His elbows also rested upon the desk, atop what looked like a bunch of paper with unrecognisable scribbly notes on it. Chances were, Gaster was multitasking, doing both the job of being the boss, while also keeping up with his other work. Somehow, for Gaster, that didn't seem like too much of a problem. Was weird to think Asgore used to sit in that seat... Now he was spending more time at home with his wife. Good for him.

"Sorry, I hope we're not disturbing you." Andrew spoke, knowing he probably had important shit to do, but Gaster just chuckled, reassuring the human that it was fine, as the reason for them knocking must have been important. "It is." Andrew nodded, while Blair bobbed her head in agreement, while her hands rested upon her hips.

"Take a seat. Though... Hold on." Gaster noticed there was only one chair sitting in front of his desk. He decided to get up from his own seat, suddenly disappearing in a flash of magic, only to reappear almost as fast, returning in front of the desk with another chair. He placed it beside the other one. "That's better." Gaster said, before teleporting back into his seat, where he was now sitting down. Blair blinked, staring at him in a state of shock. Sometimes it was still crazy to her, how fast he could do that. Teleporting. Sans could teleport too, but he never seemed to use that power too often. With his soul being the way it was and all. Sometimes it was still amazing how it took the capacity of bringing two kids into the world, who were now small children.

Blair and Andrew took a seat each, making sure they were both comfortable in the process. Gaster watched them expectantly, waiting for whatever they had to say. The human exhaled. "We have a bit of a problem. I'm sure you probably know about my family, don't you? They hate monsters... Were once part of a group that... Took you away from everyone. Kept you captive." Andrew frowned, watching Gaster's face for any kind of negative reaction. He hated to bring it up, because he wouldn't be surprised if those moments were nightmare inducing for the skeleton. The group clearly hadn't treated him nicely, locking him up in a cell, leaving him utterly battered. Andrew could hardly imagine what they might have done with him while he was their prisoner. After a short moment of silence, Gaster leaned back in his cushioned chair, seeming to nod.

"Yes, I remember." Gaster said. "Don't look so worried. Of course, it was a terrible part of my life, but I don't blame you for it." He told Andrew honestly, as he knew the human was very different from the rest of his family. Sometimes he had had nightmares, for awhile, after being rescued from that place. He had them for quite a long time. But gradually, they faded away, because he had the company of his friends and family again. Of Grillby. That man helped him a lot. "But what I question is why you are asking me why I remember them."

"Well..." Andrew started. "Sans called me. Said that... While he and Frisk were on their honeymoon, my brother - James - my twin brother, tried to kill them." Andrew told him, seeing Gaster's eyes narrow a tiny bit at what he had just told him. "He said he got away. And Sans told me to tell you, so maybe you could warn everyone. Or deal with him. I don't know." Andrew shrugged. Dealing with him likely meant killing him, but... His family were tainted. His brother just wanted to hurt the people he now cared about. The real people he now considered as family. He didn't want that to happen. He didn't want harm to come to anyone here. Not Frisk, not Blair, Sans, Gaster... Just anyone.

"...So, what you are saying, is that you aren't worried about the consequences that might fall upon your brother?" Gaster pondered, while Andrew frowned in return, staring at those two white pupils of Gaster's, that were staring at him with a questioning look. Would he be telling Gaster this, if he was worried about his brother being possibly killed? Andrew wanted to try and be naïve, think that maybe his brother could be a better person, but that was an impractical impossibility. James had been the way he had always been, for as long as Andrew could remember. When they were children, it had been very clear they were different, despite the fact that they were twins. And you would think that twins would be as inseparable as two peas in a pod. Close, like how Leo and Luna were. But they hadn't been.

James always acted like he was better. Better than him. Better than everyone. Especially monsters. For the time they had gone to any form of normal education, James would always go out of his way to pick on the monsters. Make them feel weak, stupid, pathetic. Like they were worthless, that they didn't even deserve to exist. It wasn't very difficult to eliminate the image of a monster girl, who he had made burst into tears in front of everyone. His twin had howled with laughter, like it was the most hilarious thing in the world, but Andrew watched: horrified. He knew he should have said something, told him that the way he acted was wrong. But he couldn't.

Especially not when their parents were the exact same hateful beasts. They ran an organisation, that specifically singled out monsters. It was like they had been trying to eradicate some kind of terrible disease, with the way his parents acted towards monsters. "Stay away from them, Andrew." They'd tell him. "They're not safe." Of course, he just nodded along, tried to listen to his parents, because they were his parents, and they were never wrong, right...? But they were.

They were so wrong. Everything about his family was so, so wrong. It had felt like he had been born into the wrong family, like a misplaced puzzle piece, that just didn't fit into the gaps anywhere at all. He was an odd one out, and always would be. Him and James were as different as day and night, and that was probably for the best; Andrew would never want to be like him. Monsters could be some of the kindest people he knew, kinder than them humans. His own girlfriend was a monster. His friends, who now felt like his true family, were all monsters. That's how he liked it. At first, he hadn't been so sure, when he met Sans, and they got off onto the wrong foot, and he had been so scared for his life... But it was very clear as day to him by now, that this was where he truly belonged.

"I'm not. His fate rests in your hands." Andrew said, knowing he was very certain when he said what he said. At first, Gaster didn't say anything, He seemed to be thinking over what the human had told him, before going to lean his weight back onto the desk. The skeleton nodded.

"For now, I shall just set up a meeting, tell everyone what you told me." Gaster stated, also glancing towards Blair now and then who was listening intently herself to the conversation. That's why she hadn't really had much to say, she was more focused on listening. "But, to keep things from being complicated, it's probably best you stay away from these headquarters for awhile. Considering you're identical twins, I don't want anyone mistaking you for your brother here, and getting hostile." The skeleton went on, as Andrew slowly nodded.

"Okay..." He could do that.

"But like, are you going to kill him?" Blair spoke up. All eyes went to her. "You probably should. He tried to kill Sans and Frisk, and it's clear he has some kind of motive, he probably won't just give up." The fox pointed out.

"If it comes to that, then..." Gaster murmured. "Probably. Most likely. But I just want to warn everyone first. That way, we'll be on the look out for him, if he tries to strike again."

"Good." Andrew nodded. "Because I don't want him hurting any of you." He said. Gaster managed a small smile at Andrew's comment.

"He likely won't manage anything, now that you've warned us."

Good. Andrew thought to himself again. Because he could never, ever forgive his brother, if he hurt anyone. Any of his friends... His girlfriend... He wouldn't forgive him.

Just like the other one hundred things he likely wouldn't forgive James for.