The Philosopher: Mark is this in spades when he feels like it. On his main channel, EmceeProphIt, he analyzes the symbolism in games. Their Bioshock Infinite playthrough focuses a lot on symbolism as well.
Blue Oni: Much more intellectual and serious of the two (Not that that says much at all) He makes a habit of complementing design aspects he likes and (in their Bioshock Infinite Let’s play) stopping the game to discuss symbolism.
Corey (Modestly Narcissistic)
Amazon Chaser: Admits to being attracted to strong, badass women.
Attention Deficit... Ooh, Shiny!: While Mark waxes poetic about some deep, meaningful thing, Corey will be jumping about like a maniac.
I Can't Believe It's Not Heroin!: In the 15th episode of the Spyro 2 Let’s Play, Corey drinks a 5HourEnergy and actualy seems to be under the influence of a drug of some sort.
Red Oni: Corey is a good deal more fly by the seat of his pants when it comes to playing games (usually to hilarious ends)