Speaking of Deltarune, I very much like the headcanon presented by Austin in his "The Science" video on the game
here.
For anyone who doesn't have time to watch a 12-minute video, the gist of the theory is that Kris isn't secretly evil, Kris
has PTSD. Not sure from where, but Kris's behavior and the way the trip into the dark world is framed in chapter one very much maps to a common behavior of children suffering PTSD.
The video also argues that Susie is the real hero of the game.. Becuase she plays along with and befriends Kris, and that kind of understanding and support is the key to overcoming trauma-based mental illness.
I'm not sure how well that holds up in light of chapter 2, but... Honestly, this feels more on brand than railroading the player into playing the secret bad guy.