Kris is a human Lightner and the main protagonist of Deltarune. They are presumably the human Hero of Light in the Prophecy. In a Dark World, they function ... Kris Dreemurr is the main protagonist of the indie RPG game DELTARUNE. They are a Lightner and one of the three heroes 
And when Kris shields Susie from the King in one of the game's final cutscenes you're not in control because your soul is almost vanquished. So at the end of the game Kris rips you out of himself to perpetuate the cycle 