The power of absorption in a world of magicians and cultivators

Malum was just a teenager who was going to be in his third-year learning how to fight monsters without being a magician or cultivator but a mysterious being who is revealed to be Gluttony one of the seven deadly sins came and said that Malum is his master because he didn’t want to get his pride get hurt. Malum first didn’t want him but was forced to use him in a moment with Malum seeing the power of Gluttony when his life was threatened, he decided to start using it. How much will Malum grow with his partner Gluttony who just follows him “to not get his pride hurt” (never wrote a novel before so I try it as good as I can)