>>723208321
That doesn't really make sense. The true and consistent "player character" from the very beginning of the game is the SOUL. Kris is the "player character" only insofar as the SOUL is usually controlling them, and the others are never "controlled" in the same way, we just issue them commands. Even when we follow the perspective of another character like Susie, there is never any pretense that she has become the "player character."
The SOUL is of course just a heart-shaped object and not a "character" in any meaningful sense, so it is understood as a simple vessel of our will and a means for us to interact with the game world, in a very literal way. It is a physical thing that Kris can hit and grab, but it is also an abstract icon that functions as a pointer in the game's interfaces. It can be both of these things at the same time, such as when you exploit the opening of a text box to teleport the SOUL into a closed room, because Deltarune is metafiction where the fact that it is a video game being experienced by a player is part of the story. Even if the characters in the story do not explicitly acknowledge it as such, a number of them are aware that You are watching them, and you cannot fully understand their characterization and the story as a whole without acknowledging this.