Over the last few hours, you've noticed something about Gaster. You had him pegged for an excited, enthusiastic, involved person, but the more festive your family's Christmas celebration becomes, the more he draws back to watch from the sidelines. And he looks perfectly content to do so, leaning against the windowsill, a mug of hot chocolate in hand.

A few hours ago, Alphys and Undyne showed up. After them came Asgore (Toriel was still mad at him, but for the most part, they got along alright.) Monster Kid had arrived soon after, and Mettaton and Napstablook would be coming later that night (they had already planned to do a Christmas pageant somewhere, and would be coming after.)

With the group assembled, the gift exchange commenced. Just as with Santa, no one had really gotten anything for Gaster. You overhear him saying, though, that it's more than enough to just be in space and time, with his sons again.

And you can see, with him sitting on the sidelines, he really does look happy. And every now and then, Sans breaks away from the group and stays near Gaster for a little while. Sans looks happy, too. Happier than you've ever seen him.

Eventually, dinnertime comes around. There's piles and piles of food, more than enough for everyone. In that moment, you are ridiculously happy that monster food never goes bad, because you're gonna be having leftovers for the next month and it's gonna be amazing.

During dinner, while you're all seated together, Gaster makes a request- he wants to know everything that he's missed. And, according to Sans, it was just a few months before the sixth human Soul was collected that Gaster was erased.

So Sans starts off with the story, telling how he tried to build the machine in his basement, but couldn't. You're not surprised when, since he's sitting on Gaster's left, Sans gets an arm wrapped around his shoulder, Gaster pulling him close.

From there, everyone else picks up the story, Toriel telling how she found you in the Ruins, and you describing how you made it through the Ruins, to where Papyrus carries on, telling how you and he had a great time with puzzles and japes. Undyne talks after that, describing her hunt for you, and how she eventually saw you sparing the monster kid, then saving your life. And Alphys describes meeting you in the lab, and admits to having Mettaton attack you so she could save you.

You talk about how you met Asgore, fought Asgore, fought Flowey, then reset in order to find a better ending, then reset again and again and again until you got it.

Until you went True Pacifist and found the True Lab.

Gaster asks about the Amalgamates. He assures Alphys that it's purely out of scientific interest, but you can tell she still feels guilty about it.

She makes an offhand remark about how it was her worst mistake, and she doubted Gaster had ever done anything that bad.

And Gaster just bursts out laughing. It's a loud, full laugh, with his skull thrown back and his chest out. Like he thinks something is genuinely funny. Absolutely hilarious.

"Alphys, you've got nothing to be ashamed of. I have done things a thousand times worse than that, and kept going just fine."

"R-really?" Alphys asks. You can see she's curious. You all are. "W-what-...?"

Gaster gets a faintly amused look, and seems to think back for a moment. "Weeeeeell, I could tell you about all the things I did in the human and monster war, all the weapons I made, all the blood on my hands, but that was a war; it's not surprising that I was violent, especially considering I-" he hesitates for just a moment, then continues "I saw my own brother murdered in front of me. So I won't tell you about all the horrible, awful, violent things I did then.

"I could tell you about how, once a human Soul was collected, I started the original DT project by injecting Determination into living monsters, rather than dead ones, and, rather than merely becoming amalgamates, they amalgamated and then died, where your corpses came back to life. And how even after repeated deaths, including that of a close friend, I continued with the project, until Asgore forbid me.

"No, instead, I'll tell you about how, after Asgore forbid the use of living monster volunteers, I decided my work of creating a weapon was more important than his rules. So I went and punched out holes in my hands, and used that matter to create my own test subject, who turned out to be a sentient monster. And with every experiment on the test subject, my Lv rose until I was almost as cold as I had been in the war, and when the test subject got scared and didn't want to do the experiments anymore, I forced them to. Of course, being stuck, hidden away in a lab with a nearly-evil scientist forcing it into painful experiments to turn it into a killer, the test subject started to lose hope. So you know what I did? I made another one, and had the first take care of it, to give it something to hope for, force it into holding on, so I could continue the experiments. It wasn't until they both escaped and almost died that I started to realize my mistakes."

Everyone at the table is more than a little horrified, it seems. Gaster is a lot scarier than you realized, and has a potential for coldness you've not seen in monsters.

Gaster leans forward in his seat, grinning at Alphys. "And you know, Alphys? If you want proof that our mistakes do not define us, then there is nothing more definitive than this: even after everything I did, every cruel, twisted experiment, every time he was laid out on the table, screaming in agony, even after all that... that test subject still loves me enough to call me dad. They both do."

A ripple of shock spreads through the room. Undyne actually chokes on her drink.

You're astonished. Sans and Papyrus were... test subjects?! They were raised in a lab in secret and experimented on and...

Gaster meanwhile, gives Sans a smile, only to see Sans is giving him a somewhat irritated look.

An expression of slight realization crosses Gaster's face. "Ooohhhhh...! I'm sorry, Sans, were we not talking about that, yet?"

Sans whacks Gaster on the shoulder. "no, we were not talking about that! this isn't just something you can go talking about whenever! i kinda didn't want everyone knowing i was made for the explicit purpose of being a weapon!"

"Ah. My apologies, then." Gaster looks back at everyone around the table. "Please, just forget everything I just told you. I made a mistake, and you don't need to know about any of that." Then he looks back at Sans. "As for you, regardless of what the original intent of your creation was, you are my son, and I love you very much, so you can decide your purpose is whatever you like, and I'll still approve of it. Understand?"

"... yeah." Sans nods.

"Good. Now then." Gaster looks again at the table. "This is only just my second dinner in existence, and I will not allow it to be ruined by all this talk about negative topics, regardless of the fact that I was the one doing the most talking. So, please, let's move on to other things. What has life on the surface been like?"

And, gradually, the conversation picks up again, and the question of the brothers' upbringing fades to be brought up some other time.

Later that night, after all the guests have left, after all the cleaning up has been done, and the packing up of leftover food, you wander into the living room to sit down for a little while.

Except, you find, the couch is occupied. Gaster is sprawled across it, and Sans is snuggled closely to his chest, curled up like a child, his skull resting on Gaster's collarbone. They're both sound asleep, their chests rising and falling in near unison. You can practically feel the contentment radiating off them.

You just smile and turn to go get ready for bed.

§

A/N

Welp, I've learned I have no ability to tolerate needles.

I had to get a few bucketfuls (at least it felt like it...) of blood drawn today. And the entire time leading up to it, I was fine. But when they actually went to stick the needles in me? nOPE, I'M GONNA HOLD MY MOM'S HAND AND WHIMPER LIKE A LITTLE CHILD.

And now I'm all tired and my arms are bruised. *sigh*

On the bright side, at least, my mom got me a sandwich from my favorite local sub shop! So that was good.

So yeah. There's my little rant about today.

Anyway, thanks for reading, and I hope you enjoyed it! Comments and votes are my Favorite Things, and every notification I get makes my day!