- Subterra Razenoid is a Subterra Bakugan while the Mechtanium Surge Razenoid is a Darkus Bakugan.
However, Subterra Razenoid is an antagonist due to hypnotizing Elfin to have her reveal that Drago is vunerable to Sasuke and Mecha Sonic. However, after erasing Fear Ripper from existence, Drago's rage is so intense that he forces Razenoid and his elite Chaos Bakugan out of his body and defeats Razenoid with Chompixx. Razenoid was the apparent main antagonist of Season 7. Subterra Razenoid acts as an antagonist along with the other Razenoids during Season 20, though he hides this fact from Drago. Later, Razenoid reveals his true colors and battles Drago, but is defeated.
Razenoid had heard of Drago due to Drago being a Hero of Legend. Razenoid wanted to pass his offspring, the Chaos Bakugan, to Drago as Razenoid was about to die of old age. However, Razenoid arrived during the finale of Season 3 as Sasuke betrayed Naruto (at the time, Sasuke was pretending to have seen the error of his ways) and he and Dharak took Naruto and Drago out. When Drago was knocked out, for some reason, Razenoid was absorbed by a beam of light coming from Drago's Perfect Core diamond. Upon entering Drago's body, Razenoid was rejuvenated due to all the energy in Drago (The Perfect Core, the Attribute Energies, the Element, Code Eve, Fear Ripper's life energy, and Zombie Giant-Man's Power Cosmic) and Razenoid's life was prolonged. Razenoid had planned on leaving after being restored by Drago's energy, but was trapped and ensnared by vines when a portion of Dark Marth possessed Drago's body in Season 5. However, this was apparently a lie (except for the event of his imprisonment) that the Chaos Bakugan made up so the heroes would trust Razenoid. It is revealed however at the end of Season 7 that this story was true, but Razenoid was corrupted by the portion of Dark Marth within Drago and this story was twisted to seem like a lie. Later, it is revealed that this story truly was a lie, and that Razenoid was once a Dharak, who was mutated upon being absorbed by Drago when he came to fight Drago.
In Season 6, Razenoid made his debut, haunting Drago's nightmares. Razenoid's origin was explained by the Chaos Bakugan, whose eggs he laid in Drago's body. Drago felt immense guilt that Razenoid was trapped in him for so long (since the end of Season 3). When Crazy Finger Samus came and told Naruto and Drago about Fox launching another tier war, and that Marth had enhanced Peach and Zelda, somehow causing them to join the high tiers, Drago said they had to make them stop before the princesses get corrupted, since eventually the corruption would enter Drago, and that would imprison Razenoid longer. In Season 7, Razenoid will finally be freed from Drago. However, Razenoid may have an ulterior motive that will be revealed upon his liberation since Psycho Kirby pointed out that Razenoid could've left Drago during Season 4, but didn't. Psycho Kirby's suspicions are proven correct when Razenoid hypnotizes Elfin and makes her tell Tabuu to tell Sasuke and Mecha Sonic that Drago is vunerable and in the bedroom. However Razenoid was defeated by Drago because Razenoid erased Fear Ripper from existence, which pushed Drago to force Razenoid out before defeating him with Chompixx. Razenoid retreats, but swears to get revenge. Later, Sheik battles him with Drago and wins. Then Razenoid rapidly hits the floor before Dark Marth leaves his body and sends him to the middle dimension. Razenoid escapes the middle dimension along with Kirby and Crazy Finger Samus from the silly Melee universe when they finish training. Razenoid officially joins the heroes in Season 9. In Season 20, Razenoid senses Evo Phantom Dharak's mutation into Razenoid and decides to get involved in the war himself. However, he calls the rest of the Razenoids and tells them of the war, and invites them to get in on the fun. When Ventus Razenoid asks if he should unleash them, Subterra Razenoid says no, since those Razenoid can't be controlled. Subterra Razenoid's motives are finally revealed as well. He wants all the Razenoid to unite in order to conquer the universe. In Season 22, Subterra Razenoid reveals that he and his brothers were captured by Mutant Elfin, but he managed to escape and get help. Razenoid also reveals that he betrayed Drago because he felt he could no longer stop Elfin, but realizes he was wrong and makes amends with Drago.
- For a while, it was unknown what side Razenoid is truly on. He could a protagonist since he spawned the Chaos Bakugan to save Drago. However, he may be an antagonist since Psycho Kirby said he could've left Drago anytime during Season 4 but didn't, possibly meaning he was taking in Drago's power for himself, and that Razenoid had forced Elfin to tell Tabuu to tell Sasuke and Mecha Sonic that Drago is vunerable and in the bedroom. (This was due to being corrupted). However, he is really an tragic villain.
- Razenoid's personality is somewhat similar to Nappa from DBZ Abridged, since he pesters Drago at inappropriate moments. However, this was an act to convince Drago he's not a threat. However, because he was corrupted, it may not be an act. In Season 9, it seems that this was just an act as Razenoid is more serious than when he was possessed.
- Subterra Razenoid is one of the most sadistic Bakugan in the series, along with all other Razenoids.
- Subterra Razenoid is the Bakugan version of Psycho Kirby.