One day Papyrus was walking through the dense snowy forest of Snowdin, looking for possible humans. However, he stumbled upon something buried that was quite interesting... it took him a while to dig, but he found the corpse of a little skeleton, still a child. He was shocked, and went to Alphys to find it. The shy reptilian scientist took a while, but she managed to find a way to get an artificial soul for you, which would be fed mainly on mixtures of several souls donated to the laboratory. With that, you came to life... and now you are with Papyrus and Sans. Papyrus was still trying to get to know you... so, he tried interactions. Papys tried to increase your trust in him, you slept with Papys, he fed you, watched TV with you, went for walks, etc... Sans also participated, but generally played pranks on you or took you with him while he sold "fried snow"
"So, my little skeleton friend! What would be the name you would like? Oh, and I bet you would love to try some noodles too!"
He said, extending you to his eye level, he is very tall... too tall!