Arcana DC 22 : Demogorgon's two heads are named Aameul and Hethradiah. Aameul prefers deception, and Hethradiah favors destruction. Originally, Demogorgon had one head and one mind. A mighty blow from the deity Amoth split him nearly in two before Demogorgon killed Amoth. After he healed, Demogorgon's head remained split. The two heads often disagree with one another but turn disagreement to their mutual advantage. For instance, one head struck an alliance with a powerful lich queen of the deep Shadowfell, and the other killed her to steal her powers.
Arcana DC 32: As comfortable in the seas as on the land, Demogorgon makes his home in a tropical region of the Abyss that is composed of dense jungles, deep oceans, and vast stretches of brine flats. The mightiest of the demon princes, Demogorgon commands creatures from places as as varied as the depths of the Underdark and the decadent palaces of civilization. Troglodytes worship him as a deity, sparking endless battles against their Torog-worshiping kin. Colonies of kuo-toas appeal to him for aid in reclaiming their once-great empire.
Arcana DC 37: Twins born to cultists or kidnapped and indoctrinated at a young age lead Demogorgon's mightiest cults. Each twin serves one of Demogorgon's two personalities. Invariably, such a cult falls to infighting as one high priest turns against the other, hindering many a foul plot.
Arcana DC 39 : Temples to Demogorgon often reflect the dual nature of the Prince of Demons. Builders construct each temple symmetrically: One half is dedicated to Aameul, and the other to Hethradiah. Priests, warriors, petitioners, and other functionaries dwell in whichever side of the temple better fits their personalities. A grand cathedral unites the two halves at the center.