Odion Ishtar first appeared for a short time by the end of episode 23, making a gag with the classic "Pinky and the Brain" dialogue, taking Pinky's voice and personality. This voice was not used in later appearances, instead his personality was changed to a "plain and one dimensional" character (as stated by Marik), being emotionless and serious all the time and by following Marik's instructions too literally, even causing Marik to get mad at him. He normally says "Yes, Master Marik" only. He also likes Gummi Bears and when Marik threatened him to get rid of his collection was the only moment when Odion actually answered Marik (calling him an asshole). In episode 42, he gets his own flashback explaining some of his and Marik's history (mostly Marik) during which he didn't think the tombkeepers initiation was so bad and questions why watching Disney films is a part of it; afterwards he comments, "Jeez, even in my own flashbacks I'm a minor character!"
Odion apparently thinks of Marik as the worst boss ever, and he's trying his best to drag Marik's name in the dirt when he's impersonating him. He agrees to what Joey says about Marik being an asshole, in which Marik yells at Odion in front of everyone. He seems to enjoy being scolded.
His obsession with Gummi Bears can be further seen when he prays for them in episode 40, summoning them in episode 42, and instantly waking from the whip injuries inflicted by Hank Ishtar simply upon their mention in episode 45's flashback.