(This is going to be long)
Mable P.O.V
Listen....this is going to be serious. I know I haven't tell you about my past but the reason is I didn't tell you because it's......-shudders- horrible. Well since you begged for so long, I tell you. (Ok there are body reactions like shuddering, stammering, crying or something like that).
"Long ago I was only 4 years old, I had parents when I was little. My mother was a bunny monster, and my father was human. They were very happy, helpful to other humans, and..heh I don't know how to explain it. But when I was born, I was half human, half monster. It was very...rare. I don't know how but.....a few months later there was an incident or as in accident. My father was driving to get some food for us, but then when he went to the store, a robbery came in. -sniffs- many shots were out, killing many innocent people...even.....my father. He was shot in cold blood, laying on the ground. It was on the news on tv. I cried and cried over and over and my mother was crying too. I was still 4 that time. Then few years later I was 6, I had a baby sister. Monster and humans had a....disagreement. Or.....then there was...war. It lasted for days, weeks, months. My mother was in that war too, she fought and said to me "when I'm out to fight, please take care of your baby sister and please, please be my funny bunny. Please be together while I'm away, but when I come back, please be happy for me. And stay happy.". That look on her face, she was in tears yes but happy too. I hold my sister in my arms and saw her left. She fought and fought for days until.....she....she -starts to cry- she died by a human in cold blood. I ran and ran far away with my sister in my arms and ran away form that long war. I was in the woods finding a home. Until I saw a shack near the edge of the country side and I went in. It was perfect for us. I found a big bed for me and my sis until I heard some humans. They were looking for me and my sis and I hide. They found me and tried to grab me out. I hold on and my right eye was glowing white with a white eye flame. I teleported them out to an abyss and I sat down. My eye was still glowing and said "don't worry sis I'll protect you....from all the horrible things". Then she started crying a little. I tried to help her calm down until a little monster came into the old shack and I calmed her down by telling her to look at me with my tears, she was laughing a little and stopped but smiled. I smiled back and took a little peek at that monster by a corner. It was a skeleton, and he was the same age at me but with his baby brother. I came out of the shadows and he looked at me and I started at him. I smiled and so did he and we were friends. A few years later we took care of each other and looked after our siblings. He never told me his name and I told me my real name. We were both 9 years old and he told me he had the same powers as I had, I told him I'm not alone. Our brother and sister were 5 years old, playing their toys while we were stealing and begging for money. We weren't caught by our magic, but we were pretty well known. We were happy until he told his feelings the next day at night about me, I was finally happy that he told me, I told him about my feelings too. We were both in love but in a determined way. We were best friends that time, so did our siblings. He told me his name and I was happy. And also told me his brothers name and I told him my sisters name. The next day we practiced and begged and steal for money. But then....-starts to cry a little- then...then.....we got separated by some humans. They were the Ansleys. The skeleton was sent underground and I was still at the surface but.....my sis and his brother and himself was sent in the underground. I was alone. A couple years later I was 14 years old, trying to bring them back again but there was no way, I tried to escape but the Ansleys were so mean and powerful to me. I was so weak, I couldn't use my powers anymore. Everyday I curled us in a ball, crying, thinking I didn't have emotions anymore. But I still have feelings for my friends and my sis. When I was 17 I ran in the woods trying to find my friends and my sis again. It felt like I had the chance to see my skeleton friend again. Until I fell in the underground and then I went to this little town called Snowdin. Then I was asleep in a random house until the next day.......-in tears but happy tears- I found them....they were named....Sans and Papyrus.

(FYI she didn't find her sister but she tried all her might but then her words are....Never Give Up).