Sartorius was once a simple fortune teller until he was possessed by the Light of Destruction. He then became a powerful duelist bent on destroying the world through any means necessary, using his powers as a fortune teller to predict his opponent's moves. He was returned to normal after being defeated by the combined efforts of Jaden and Aster, and later helped them later in the series.
Sartorius uses an Arkana Force deck based on tarot cards, gaining effects depending on which side the coin lands with one positive and one negative. His ace monstersare Arcana Force EX - The Light Ruler and Arcana Force EX - The Dark Ruler, very powerful monsters with positive effects regardless of whether you flip heads or tails.
Asta wanted to find who ki lled his fatha, so he got inside a weird cult in order to "learn about his fatha" and eventually find the criminal.
But this extraterrestrial dude tricked him and deceived him. Then the ET became a father figure for him.
To make it even worse and complex than that, Sartorius, this extraterrestrial is also being manipulated by some entity who makes people believe in something hierarchical and fallacious. Hierarchy = False god.