"Its a Classic"

Sans or in this case Value once was a classic just like dust,killer etc.. In Value's timeline he never did anything to stop the resets he had just lived with it. Many routes played over and over again, genocide, neutral and pacifist. But they were constantly changing due to the resets. Sans was tried of trying to stop it so he kept reliving the moments over and over again. But what no one noticed was that the constant use of the "reset" button was affecting the "Fun value" of each timeline. Because of the constant change of routes the fun value began to act on its own. How will this effect classic well you'll have to dig deeper into the story to find out...