So, wether or not Chara was evil BEFORE that, (I don't think they were. When Frisk gains LV and EXP, the name doesn't change to 'Frisk', it stays 'Chara.' That literally means that because they share the same soul, Chara is also getting the LV and EXP, not just Frisk. When you look in Frisk's inventory/stats, it doesn't say 'Frisk' it says the name YOU put, which may or may not be 'Chara.' In case you didn't know, the sprite for the red soul is called 'Our Heart' which means that Chara is using Frisk's soul to stay alive, so technically, they share the same soul.
Just to stop all the 'Chara isn't evil!!!!!!1!1!1!1one!!!' comments, heard me out:
