Nah, actually the player is a bad person if they choose the genocide route. Chara is dead most of the time, and in the Pacifist run, they help you save Asriel, they really care about him. Chara, just like Sans, has to watch everybody they care about die over and over, laughing the pain away. The player corrupts them, and remember, they are just a kid, not even a teen. They are used as a scapegoat for murder because the player doesn't want to acknowledge that their actions have consequences. Therefore, the Genocide player is a terrible person, not the kid who watched everybody they cared about die.