Beelzebub finally comprehended why Darius had been verbally farting all this while.
Upon reaching this conclusion, his body trembled, but not in fear, rather anger! This was preposterous, unheard of, and vile!
Basically, Darius was asking him to put on a show with him!
To become an actor in the drama of the 'Insects' genocide' to please the Goddess so that he and the other members of his race might gain a better standing when it was time to meet her.
During the first Quest, the Titan God of Death had cleverly done things in a way to show favor upon to the Goddess, who would eventually show her favor back to him.
Darius now presented Beelzebub with the perfect opportunity to do the same as Thanatos, only that his role would end with his head rolling.
What actually angered the Lord of the Flies was the fact that this proposition was… truly enticing!