>>719001682
Chara is understood to be the player surrogate for 99% of the game. You play as Chara, who was somehow resurrected and attached to Frisk's SOUL, and your influence on the world (such as the power to SAVE) is understood as theirs.
Deltarune does not have this middleman as part of its framing device, and the separation between the player and the player character is established immediately rather than being an endgame twist. In Deltarune, You are contacted by a meta character who is already familiar with you from your experience in Undertale and you are brought to the world of Deltarune to affect change with your Determination, with You being represented by the red SOUL. There is no suggestion of a third party involved to muddle the waters and confuse the chain of custody here, You were meant to control a (presumably) soulless vessel but instead end up controlling Kris via their SOUL.
The SOUL is how You are represented in the game, but it and you are more than that, and even the characters who are aware of You know it. When Kris stuffs you into a couch or a box, you're only physically limited as much as it serves the purpose of the game - at any time you could exploit game mechanics to simply appear somewhere else. When Kris physically grabs the SOUL, they don't stare at it - they turn over their shoulder and look directly at You, where they know you're watching them from. Kris's SOUL might be a physical thing but as an extension of You it's become more than that - even if it shatters and Kris dies, You just take it to the Game Over screen and come back.