He is the founder of Inversion Therapy, which attempts to help people conquer their fears. Fontaine wrote the book "Fear It? Do It!", although he has no qualifications for this. Lazlow describes him as 'a former sociology professor' on WCTR's Entertaining America, although he is a qualified gardener.
Darius hates religion and in 1992, he has an on-going feud with Cris Formage, the Epsilon Program's founder and cult leader, and Lazlow. Lazlow had a restraining order against Darius after he encouraged Lazlow to sleep with his grandmother, although Lazlow slept with his mother and was almost imprisoned.
In Grand Theft Auto V, Darius Fontaine used to own a self-help center, Children Of The Mountain, but had lost it in a legal battle to Brother Adrian who is still continuing the work of the center. Darius is only mentioned once in the FAQ section of www.childrenofthemountain.com.
- Darius shares his surname with Beatrix Fontaine, a fake psychic who apperared in Grand Theft Auto IV, and Harlan Fontaine, the main antagonist in L.A. Noire, another Rockstar game.
- Darius is one of several celebrities from the 3D Universe to have a star on the Vinewood Walk of Fame in Grand Theft Auto V. His is located on the southeast side of the Cinema Doppler, directly across the street from the entrance to the Von Crastenburg Hotel.
- His "inversion therapy" may be a reference to "aversion therapy", a now-discredited form of psychological treatment which involved combining stimuli with some form of discomfort, and was most infamously used as a "cure" for homosexuality.