This oc was originally a soul, she went to alphys in hot lands to help with tests since she had nowhere to go, after awhile someone found the soul, trying to take it to asgore, then Alphys warned the two people that the soul had escaped, despite the fact alphys knew the soul wouldn't harm people she lied about the soul, then the soul entering sans' body to help stop those two people, then sans making the soul their body, they got to customize the way they look and decided that this is who they wanted to be, if sans could not make it to the snowdin forest in time they would greet you, then sans showing up and them going ahead since papyrus does not know her, meerly nobody properly knows her.