>>724890706
Because Kris is a deconstruction of the choose-your-own-character idea. You are meant to initially see them as a vessel to do your bidding, before slowly growing to understand over the course of the game that they're a unique person with a backstory, desires, motivations, and everything that existed far before you ever showed up to yank them around. Frisk has no such desires, possibly because they're generally more submissive or possibly because the relationship between the soul and the character is different in Undertale. but that's the text of Deltarune