This version of Gaster never fell into the Core. Instead, over the years, he had studied the Void and tested the abilities and effects on monsters and such. Creating the Followers, the ones who willingly applied for the tests. Even tho his obsession with the Void bordered unhealthy, he was still a good man, trying to help the monster citizens in any way. Once they went above ground and the war started, it all went wrong. In a secluded testing area far into the Canadian wilderness, he conducted his tests away from all the monsters, as to not cause harm, but during a observation of Void radiation, he was thrown into the testing room. He was bombarded with the radiation, the force of the radiation moving into his body cracked his skull, leaving a spider web pattern all across his skull. He was found two days later, the lab in tatters, by a Metta-Unit squad, and he stood in his lab, still working. When he was brought back to the place, he told Asgore he had a breakthrough, later he was found talking to his shadow in his room. The witness was found hung in his room.
He wears a dark red lab coat, with white trim, that overs his whole body. His skull is cracked in a web pattern and his left eye is hollow. His hands are shaky, especially when being argued with.
He has control over all the base soul traits, and he attacks with them in orb shapes, but the orbs can morph into weapons of various types.
He also can combine them into other unique soul traits.
His shadow can move on it's own accord, and can hold onto a persons shadow to control their movements, but it still follows a shadows normal rules.
His hands steady when he is fighting.
He acts nice, and caring, usually giving little speeaches to the smaller monsters. But he's words have a silent dagger behind them.
When alone, he is very violent, eventually leading to Alphys 'accident;