>>713605161
You are (You), Frisk owns the body and SOUL, and Chara is the ghost of a dead kid who acts as the game's narrator. If you kill people, Chara takes more and more control over the body.

>>712601001
tfw i have an iPhone

>>712586463
They were there the whole time, they were the narrator.

You start the game possessed by the ghost of Asriel's long-dead brother. They were a mildly sociopathic shitkid who you taught to be a complete fucking psychopath via the Genocide Route (and also fed them a ton of XP when they started off with higher LV than you due to being a sociopath). They're fine on the Pacifist route, though still a bit of a shitkid.