"I just realized what the 'G' stands for in Yu-Gi-Oh! GX
... don't watch it!"
- Angst? What Angst?: Marik only needs a few seconds to get over the trauma of having killed his own father. Of course, this could be seen as a Justified Trope considering what his father was like.
- Badass Biker: Young Marik aspires to be this when he grows up.
- Digital Piracy Is Evil: Downplayed. Kaiba plans to download the Yu-Gi-Oh! 10th anniversary movie illegally, "just like everybody else".
- Evil Versus Evil: Yami Bakura (assisted by Marik) goes toe to toe with Melvin.
- Idiot Ball: Odion plans to hide Marik's absence from their father by stuffing a fluffed pillow in Marik's bed.
- Imaginary Friend: Melvin started out as Marik's imaginary friend, but things got out of hand quickly.
- Mundane Made Awesome: Marik has been underground so long that everything on the surface impresses him. This includes poverty, disease, and rags.
- No Indoor Voice: Marik, during the worst time possible.
Ishizu: Remember, we must be very quiet so that we don't disturb our father.
Marik: HEY ISHIZU LOOK AT THAT THING OVER THERE I WONDER WHAT IT IS. Loudly do I wonder about it.
- Poor Communication Kills: Yugi calls Ishizu out for not bothering to warn anyone that they were locked in close quarters with her brother's Axe Crazy Super-Powered Evil Side.
- Remembered Too Late: Shadi comes to warn Ishizu and Marik that something terrible will happen if they disobey their father after they've already done so.
- Rule of Cool: After deciding to face off with each other, Melvin and Yami Bakura both take out freaking lightsabers.
- Shout-Out: Marik plans to befriend a seagull, find a giant octopus, and fall in love with a handsome prince when he's above ground, ala Disney's The Little Mermaid.
- Soundtrack Dissonance: Hank's brutal Family-Unfriendly Death is accompanied by "Cats in the Cradle".
- Strange Minds Think Alike: "A fluffed pillow...? That's ingenious!"
- Ted Baxter: Hank Ishtar describes himself as "the finest human being in the world".
- Weaksauce Weakness: Melvin is an unstoppable force of death and destruction... as long as Odion isn't near him and fully conscious, in which case he goes back to being Sealed Evil In A Marik.
- What the Hell, Hero?: Yugi calls out Ishizu for being a bystander/contributor to Marik's Hilariously Abusive Childhood.
- Yaoi Fanboy: Marik finds a very suspicious comic book lying around that gives him "cravings".