If XTale Gaster...
became a witch, within his labyrinth he would present his original self as a conductor, waving his hands through the air. With each motion, one of his creations would come to life around him in the scarily perfect way he had imagined his world.
But every time he noticed even the slightest imperfection in his work, he would start over again and again, growing more frustrated and enraged with every reset.
The people who enter at first would believe they are in the original universe they once knew, only to eventually discover XGaster conducting new creations before them. The world around them would begin glitching and twisting, reality becoming increasingly distorted as he endlessly restarts his creations over and over again in pursuit of perfection.
The more irritated he becomes with the way his creations unfold, the more his "original self" within the labyrinth begins to resemble his corrupted self. What angers him even further is having his progress interrupted. He will send his creations after the attacker, using them to remove whatever stands in the way of his work.
If he witnesses his creations being defeated, or acting in ways he does not approve of, he becomes increasingly frustrated by the fact that they are not behaving as he intended.
With every flaw, every mistake, and every tiny detail he notices that does not meet his standards, his anger continues to build. As his frustration reaches its peak, he gradually transforms further and further, until, like a larva becoming a butterfly, he blossoms from a cocoon and emerges in his true witch form.
