In Kaiba's own words, "Pegasus is ruthless. Camp, yet ruthless." This description is accurate - from his eccentric style of overdress, to his foppish, borderline-effeminate style of speech, to his incredibly pretty-boy looks (Pegasus disagreed with Marik who called himself the girliest male Yu-Gi-Oh character). Like this, Pegasus fits the analysis perfectly. He has a habit of declaring everything "fabulous," and he also seems to have a liking for the Spice Girls (Croquet complains about having to see the film Spice World over and over again). He also enjoys sponge baths. It is at first hinted that Pegasus is gay, due to Bakura's gaydar pointing toward his castle. In episode 16, however, he remarks that he "can't have people thinking he's straight," for reasons unknown, and in episode 18 it was revealed that Croquet used to be in a relationship with another henchman. LittleKuriboh later confirmed that the gaydar was pointing to Croquet, not Pegasus, who is indeed straight.
Like in the original series, Pegasus originally had a wife named Cecilia and used Duelist Kingdom as part of his plan to resurrect her. The reason she is not alive, however, is because she apparently has an odd habit of exploding in front of Pegasus. Cecilia is the second most beautiful person he had ever laid his eyes on (Pegasus himself being the first). According to his notes, Pegasus wanted to use KaibaCorp's technology and the Millennium Items to bring her back (Téa noting fanfics make more sense than that) and being more "confused" than evil in the Marik's Evil Council of Doom short.
In episode 19, after his defeat at the hands of Yugi, he loses a Shadow Game to Yami Bakura, which involved "Ancient Egyptian Laser Beams." Yami Bakura then proceeds to extract his Millennium Eye, although he runs into trouble as he ends up pulling the wrong eye out. Pegasus is last seen being carried by Croquet, who claims that Pegasus is feeling under the weather, although Yugi believes that he is dead (even though he is alive in the anime series and is shown later in the Abridged Movie) and Tristan even adds, "He died as he lived, draped in the arms of another man," possibly not convinced on Pegasus' sexuality (or at least still believing the events of episode 16 to be a dream). Because of Yami's LittleKuriboh impostors, Pegasus will never be able to watch the Yu-Gi-Oh! Abridged series again.
Pegasus was mentioned once again by Shadi in Episode 41. He was seeking to exploit Egypt's third-world country status, and came dangerously close to breaking the fourth wall doing it. Shadi showed him the Pharaoh's tomb which he was as happy as "[a] woman after being given shiny new cage to sleep in" as said by Shadi. He made this into a children's card game. Croquet reported that everybody involved with making the cards died, especially "Chad from accounting." He made the cards himself, comparing it to "stealing from the Egyptian Gods' deviantArt account". That night, he had a dream where Shadi said if the Egyptian God cards fall in the wrong hands the fourth wall will be destroyed. He then hid the cards with the help of Ishizu.
In the Abridged Movie, Pegasus acts more camp and gay than before, even going far as flirting with Kaiba and asking to make love with him. LittleKuriboh said that he does this in an attempt to psych Kaiba out. Apparently he likes Priscilla: Queen of the Desert and that his favorite dream is starring in it. Even his snoring is girly, saying "Ooooh" when doing it. Also in the movie, he is credited as him/herself, implying that the reason Pegasus may be so effeminate is because he may be a woman.
In the second Council of Doom, Pegasus begins to show more of his sexual ambiguity by applying make-up, including eyeliner. He also appears to be a pedophile as he wants to show Rebecca his "funny bunny," although he may again just be trying to fool with his image (or he may have meant it literally).