Swap Sans finds out what it really takes to be a royal guard.
"Alphys, I'm not a child!"
"I didn't say you were, Sans, but—"
His eye lights blazed. She heard his bones begin to rattle. "But you thought it! You think I'm just a kid, that I'm just playing at this. You think I'm pretending to be a guard because it's fun for me or something and that if you indulge me long enough, I'll eventually lose interest and move on to something else. I'm not playing around here, Alphys! I've wanted this for years and I'm tired of you telling me no!"
"Sans, listen—"
His eye lights blazed, not in his usual orbs or star shapes but a flare of magic that licked the edges of his sockets. His bones rattled and clacked together. He clenched his hands into fists in his gloves as he stepped toward her and shouted. "No, you listen! I have wanted to be in the guard since I was six years old. My dad was the head of the guard and he was a hero, and I wanted that! I wanted to take care of people and keep them safe. I wanted to protect my brother and my friends. I've spent years in training. I've done everything you've asked me to, all this time. I'm ready to actually be a goddamn guard!"
Alphys actually stepped back. She had never seen him like this before. She held up both hands. "Now l-look, Sans," she said, her childhood stutter coming back a bit, as it did when she got nervous, "I n-never meant to make you feel b-bad, or like you w-weren't good enough. I just…you're a kindness soul. Your instinct is to take care of people, not to fight them. If a human comes, I need guards who are willing to attack."
"I know that," he huffed. "I know the queen's orders. I've got puzzles prepared for any human who comes along. I've got the capture protocols memorized and the capture zone prepared, just like you've told me to. I'm ready for a human. I just want to be officially qualified to capture one when it comes."
"I know, Sans," Alphys said placatingly. "You're always prepared. But humans re dangerous. What if the human attacked you? You have 1 HP."
"I've beaten you at fights with my low HP," he snapped. "You know I can hold my own against a stronger opponent."
"But I haven't ever really been trying to kill you, bonehead." She could feel her temper rising. "Fighting is all about intent, Sans. A human's intent will be to kill you. Would you be prepared to kill them? I don't think you could do it."
The flames in his eyes faded back to his usual blue pinpricks. He seemed to deflate a bit. "I would hate killing anyone," he said softly. "I don't ever want to."
"A guard has to be prepared to kill."
"I said I don't want to, not that I wouldn't." His voice was suddenly hard again. "If the human gave me no other choice, if they hurt someone I love — if they hurt Papy — then I would fight until either they were dead, or I was. I hope I don't ever have to, but I would. If I needed to."
"Would you kill if I ordered you to?" Alphys asked. "If I told you that you had to do it, to keep everyone safe, would you kill a human? Even if they hadn't attacked anyone yet?"
"I don't know."
"Would you kill to take the human"s soul, so the queen can finally set us free?"
"I don't know," he repeated.
"I can't let you in the guard until you do. We can keep training, and hanging out, but that's the real requirement."
He nodded slowly. "Okay," he said, his voice too calm. "I understand now. Thank you, Alphys. I'll see you later. I need to get home."
He walked out of the house. Alphys watched him go, her soul aching.