In the Gizmotale AU, Mecha-Asriel, also known as Rei, is a one-of-a-kind Goat Monster Robot who was a scrapped prototype that was abandoned in the Underground by his original creators, whose whereabouts are unknown. He was taken in after being found by Gaster and Frisk when they picked up his signal. He is kind, caring, shy, loving, and sweet. Being 7 years old, he is younger than Robot Asriel, who is 9 years old.