Loving Every Bone in Your Body

Sometimes, you liked to imagine that Frisk was this kind and sweet because of you. That, maybe, you had lived up to your promise of being the best sister you could be when they were first born. ...That you taking the brunt force of your abusive parents was worth it.
You had protected them from the reality of your family and... you knew that you had to protect them now.
You were Determined... To stay Kind.

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Arc 1 (Chapters 1-18), MAIN GAME: In which Frisk has an older sister (green!soul) that is, for some reason, aware of the resets. After going through a month of 'what if', she decides to follow Frisk on the journey.

Arc 2 (Chapters 19-23), TRUE END: Though you were alive and breathing, you and Frisk had another challenge to face, this time with less blood and guts. Now came the true test- gossiping neighbors, new schools, and politics.

Arc 3 (Chapters 24-41), EPILOGUE: You and your kid sibling, Frisk, freed monster kind over 10 years ago. Everything couldn't be more perfect and all you wanted to do was settle down. That is until you realize you can't remember the last 10 years of your life. Things go to chaos quickly as your memory and sanity start to slip. The only monster who seems able to help you is a man that no one can see or hear, but you. A man named W. D. Gaster.

Arc 4 (chapters 42-??), PROLOGUE: You had traveled through the Underground with you kid sibling in tow to save monster-kind. 10 years later you did it again, albeit you were alone and the journey was scattered between the different alternate realities of your own to regain your missing memory. Now "home", you must pick up the pieces of your broken life, hopefully to piece them together to create a new one. While you're at it, you suppose you could help the wayward skeletons that had accidently followed you home from their universes.