Gareth flaunts his "team leader" status, despite his desk mate, Tim Canterbury, highlighting that it is a meaningless title simply entailing more responsibility for the same pay. Nonetheless, Gareth takes the job very seriously. His attempts to throw his inflated sense of authority around the office rarely work, and it is clear that no one pays any attention to him. He does display certain concerns for his workers, mostly regarding health and safety matters.
Tim plays numerous pranks on Gareth, such as hiding his computer, putting his stapler in jelly (a prank that was reprised in several other versions of The Office, including the American version), gluing his phone so that the receiver cannot be picked up and then calling him. Tim plays on Gareth's naïveté by discussing warfare with language which could be interpreted as being homosexual in nature, e.g. "the enemy has discovered your camp...and they've all entered your hole", "taking a man from behind" or "could you give a man a lethal blow?". In the Christmas Special, Gareth has become manager, but Tim still plays practical jokes on him by stealing his keys and then locking him in his office.
Gareth constantly displays naivety and, like Brent, can be unintentionally discriminatory. For example, Gareth attempts to disprove accusations of homophobia by mentioning that his CD collection includes George Michael, Pet Shop Boys and Queen, remarking that "they're all bummers". Queen features prominently among his favourite music. His favourite band of all time is Mike + The Mechanics, which is mentioned derisively by Tim in the bonus features of the series 2 DVD.
Wherever possible, Gareth constantly boasts about his military skills and how they might come in useful in an office environment, such as how to kill a man with a single blow. Despite his experience in the Territorial Army, he exhibits a selfish, egotistical nature and seems to be physically weak. It is quite probable Gareth inherited his love for the military life from his father, who was involved in the army some years ago.
Keenan enjoys kung-fu films, and he drives a Triumph TR3 which he bought for £1,200 and restored. The vehicle is now believed by Gareth to be worth around £3,000. Gareth is shown to have very little self-awareness, believing that his unthoughtful comments and occasional macho bravado are completely appropriate and will earn him the respect of his co-workers. His lack of self-awareness is also displayed when Tim and Dawn repeatedly insinuate homosexuality through questions about his military service without his understanding.