Gus is a dog Yōkai with short brown fur, long hanging ears, a black and pink nose, sharp teeth that protrude from his lower jaw, green sclerae, and a large, muscular figure. He has four fingers on each hand and three toes on each foot, white claws, and a short tail. He wears a black collar around his neck with a silver hexagon-shaped key attached, reminiscent of a dog ID tag.
Gus is relatively laid-back and intuitive, able to consistently sense that things are amiss when the Turtles are lurking around him in “The Ancient Art of Ninja Hide and Seek”. Despite this, Gus is easily distracted and his love for indulgence can get in the way of his guard duties.
Gus debuted in "Bug Busters" where he was sent by Big Mama to hunt down Leonardo. After Leo rescued Raphael, Donatello, and Michelangelo before they could be used as rodeo clowns in the Battle Nexus, Gus found them. Mikey used a ball to distract Gus where he threw it down the hall, however, Gus caught up to the Turtles at Big Mama's office telling Mikey that he should never initiate a game of fetch he is unable to finish. When Baron Draxum had his minions Huginn and Muninn target the jar of Oozesquitoes, Gus attacked them. During Draxum's fight with Big Mama, Gus saw the ball rolling into the Big Mama's vault and followed it.
In "The Ancient Art of Ninja Hide and Seek", Gus was followed by the Turtles for multiple days as they attempted to retrieve the tag attached to his collar for Splinter. He found them eventually, but lost sight of them as they used their newfound stealth techniques.
- Spike protrusion: Gus can manifest spikes on his body at will to be used defensively against attacking opponents.
- Enhanced smell: Gus has a powerful sense of smell and uses it to find unwanted occupiers of the Grand Nexus Hotel.
Friends and Allies
- Big Mama: Gus works for Big Mama as a guard of the Grand Nexus Hotel. He seems to have no issue following her lead and seems to live somewhat luxuriously at her hotel. While he speaks quite casually towards her, he seems to be somewhat afraid of her and is willing to lie to her in order to escape her displeasure as seen when he thinks that she wants him to answer for chewing up several slippers at some point prior to "Bug Busters".
- Otter bellhop: Otter bellhop is a colleague of Gus as employees of the Grand Nexus Hotel. Gus and him worked together to try to disrupt the Turtles' plans in "The Ancient Art of Ninja Hide and Seek".
- Fox bellhop: Fox bellhop is a colleague of Gus as employees of the Grand Nexus Hotel. Gus and him worked together to try to disrupt the Turtles' plans in "The Ancient Art of Ninja Hide and Seek".
- Owl bellhop: Owl bellhop is a colleague of Gus as employees of the Grand Nexus Hotel. Gus and him worked together to try to disrupt the Turtles' plans in "The Ancient Art of Ninja Hide and Seek".
- Baron Draxum: Draxum is an enemy of Gus as he is of Big Mama. He attacked Draxum's henchmen when he broke into Big Mama's office.
- Huginn & Muninn: When Huginn and Muninn traveled to the Grand Nexus Hotel alongside Draxum to reclaim his Oozesquitoes, Gus intercepted their efforts and attacked them in Big Mama's office. He ended up being distracted by a tennis ball and released them.
- The Mad Dogs: As enemies of Big Mama, Gus attacks the Mad Dogs whenever they are spotted trespassing in her hotel.
- Raphael: Gus used Raph's scent to track down Leo in "Bug Busters".
- Michelangelo: Gus used Mikey's scent to track down Leo in "Bug Busters". After tracking down Leo, Gus found him and the other Turtles in a hallway, but Mikey distracted him with a tennis ball, causing Gus to chase after it.
- Leonardo: Gus pursued Leo after he ran away from Big Mama and her other staff and found him. He was unable to apprehend him, however. Later, Gus recognized Leo when he tried to steal his ID tag from him while watching a Battle Nexus match in the Grand Nexus Hotel sporting lounge.
- Donatello: Gus used Donnie's scent to track down Leo in "Bug Busters".
- Hamato Yoshi / Lou Jitsu / Splinter: While Gus was unaware of his presence, in "The Ancient Art of Ninja Hide and Seek", Gus was at times prevented from detecting the Turtles by Splinter.
- The ID tag of Gus' collar also works as a key to a drawer as shown in "The Ancient Art of Ninja Hide and Seek".