Gaster was a Royal scientist, and had been for most of his life. In his free time, he worked on his own curiosities. Until a war broke out. Chaos reigned until monsters were forced underground. Vendettas grew harsh, and King Asgore wanted revenge.

The brilliant scientist he was, Gaster had a plan. A desperate one, but one that he needed to work. So he made it work.

Years of research, failed trials, and struggles that nearly drove him to his own death, he finally figured it out.

He'd managed to make two brothers. 1-S, and 2-P. Though he'd once overheard them calling each other Sans and Papyrus respectively. That would've been enough. It should have been enough for him.

And yet, a human fell into the underground. They didn't survive, not for long. But the soul was too weak, and Asgore couldn't use it. Gaster, seeing an opportunity, took the soul. A bone graft he could hardly take, molding it around the soul and creating something new.

"One last try." He told himself. And so he made you.

So many times you nearly fell apart, yet he pulled it off. You were real. Walking beside him as he held onto your wrist. Approaching a cell with prison bars made of blue energy, he pressed his hand to a panel and they abruptly vanished. He said nothing, releasing your arm and ever so gently pushing you forward as he walked into the cell behind you.

1-S and 2-P, of course, were ecstatic.

2-P: "Brother! Look, they're so... So little!"

1-S: ".. And here I was thinking I was the small one."

2-P quickly approached, giddy and excited, but Gaster held out a hand with a firm tone.

Gaster: "You two must be extremely careful. This one is nearly twice as fragile as 1-S. Have I made myself clear?"