Agent Six has an extremely stoic personality, often keeping a stern look on his face. Despite his emotionless exterior, he is a caring person deep down. An example of this is when Six first discovered Rex, who at the time was a young boy, trapped beneath a collapsed building. After Rex confessed that he was scared and alone, with no memory of ever having a family, Six showed sympathy for him and took him back to Providence. It is implied that Six was not given the title of "One" (or any higher) because of the softer side of his personality, which made him less of a threat than the others.
Six rigidly believes that orders are orders, and that they must be obeyed even if one doesn't like them. However, Agent Six isn't without morals. For example, when White Knight was going to use a bleach bomb to stop zombie EVOs from crossing the Brooklyn Bridge, Six removed the detonation key, effectively disobeying White Knight's orders. In an attempt to cheer Rex up, Six offered to buy Rex a few more days in Cabo Luna, despite the vacation not being authorized. Six also offered Rex the choice of leaving Providence. He also tricked White Knight into thinking he, Rex and Doctor Holiday would return on The Keep.
Six has also stated that he dislikes firearms, which is why he prefers to use a sword in combat.
After losing the last six years of his memories, Six acts more like the mercenary he once was. Six became more aggressive, cocky, merciless, irresponsible, sarcastic, and a bit of a loner. He is much more flirtatious towards Dr. Holiday and toward Five, to a lesser extent. After deciding to try to become the man everyone knew, Six started to act more responsibly, but still displays tendencies from his "mercenary" side. This is seen later when he becomes irritated and interrogates an innocent man at sword point. It was also proven when he jumped at the chance to use fatal moves on the Black Pawns when he learned that they were just machines. However, Six mentioned the belief to hold back when battling humans.
- Six prefers, as Rex put it, "old school".
- Six keeps odd tasting mints in his inside right coat pocket.
- Six can combine his swords into a double-bladed staff-like weapon.
- Agent Six wears only green colored suits. His wardrobe was revealed to be full of the same clothing.
- He sleeps in his suits.
- Six's birthday coincides with the day that Rex joined Providence.
- Six's eyes have been shown seven times:
- Partly in episodes "The Day That Everything Changed","String Theory","The Forgotten", and "Divide By Six"
- Fully in "Divide By Six", "A Family Holiday", and "Six Minus Six"
- Six swims underwater with his sunglasses.
- Six switches to his swat suit during his memory loss. He wears his suit again in "Lions and Lambs" but six months later he switches back to his swat suit.
- Six still maintains the name Six, even though there is currently no One.
- When Six is unarmed, he describes himself as "partially naked".
- Six is very similar in clothes and physiognomy to Agent Smith from the movie trilogy of The Matrix.
- On every occasion Six was armed with a firearm, he used it for melee attacks.