In 2000, Greg Weisman revealed on Ask Greg that Percival was one of eight survivors from the Arthurian legend still extant in the Gargoyles Universe. In particular, Greg elaborated that Percival was Duval, a character that had first been mentioned in "The Journey" (the first episode of The Goliath Chronicles, written by Weisman). He was described as follows:
- Sir Percival. The Fisher King. Mr. Duval. Founder of the Illuminati. Spends a lot of time in Castle Carbonek, a sort of mini-traveling-Avalon, where time passes differently. Also uses the Holy Grail to maintain his youth, though at a very real physical cost, due to his, shall we say, sins. 
Greg also revealed that Sir Percival/Duval was the husband of Lady Blanchefleur, the Queen of Carbonek, writing "She lives there and uses the Grail. The only cost being her estrangement from Percival." 
A year later on the website, Greg divulged that the use of the suffix -val in Duval's name was specifically intended to reference this connection. 
Duval first appeared in person in "Rock of Ages", published in Gargoyles: Clan-Building, Volume Two, alongside the new character Peredur fab Ragnal in Carbonek. Duval is depicted as having cybernetic prostheses in place of his left eye and at least one of his hands, and has a contentious relationship with Blanchefleur. He is not particularly depicted as being married to nor having had any prior relationship to Blanchefleur, except that he and Blanchefleur are the two people that Peredur loves most in the world. Also, Duval is depicted as been a Number Two rank in the Illuminati, which would be unusual for its founder, and Peredur seems to be in a position of authority. Furthermore, Peredur is a Welsh equivalent of Percival, and the Stone of Destiny refers to King Arthur as Peredur's "master". This has caused some confusion among fans. Nevertheless, Greg has said that nothing has changed from his original plans.