Trebol is a very bedraggled individual. He has dark hair that is worn as a bowl-cut. He wears a small pair of sunglasses and has a broad flat nose, which is commonly seen with snot hanging out of it. He has a long, thick beard and some stubby hair on his upper lips. He also has a small scar just above his right eyebrow. He holds a scepter with a club suit design on the top.
His lips are a bit thicker than normal and his teeth are round and have some space between them. He has a prominent hunch and appears to be considerably taller than normal people, although his slouching back takes some height away. His attire consists of a long coat with a ring-pattern on it. He does not wear any footwear and is always shown with bare feet, but wears a mid-length chained-shackle on each of his ankles, which are not linked together. He usually looks as if his body is made from a thick substance that is secreting off his body. His body type, posture, and attire make him look like a giant snail. Of the executive officers of the crew, his build is in-between Pica's and Diamante's, with a prominent and permanent hunchback.
Trebol seems to have a problem with how close he gets to someone with whom he is talking, making people comment that he is too close.
He is somewhat bold and insensitive, as he casually asked Baby 5 if Doflamingo killed another one of her fiancés, as well as asking Baby 5 to marry him as a joke, knowing that it would make Baby 5 feel compelled to help him. Trebol can also act rashly and violent, as upon realizing that the Straw Hat Pirates are attacking Sugar, he instantly threw a ship at the Officer Tower without considering the damage or risk to Sugar, while cruelly setting fire on the captured dwarves. Despite his insensitive and cruel behavior, he has no tolerance for anyone who insults his family, as he grew angry when a peon giggled at Pica's voice.
Like many One Piece characters, Trebol has a distinct laugh: "Behehehehe".
Trebol occupies the Club seat in Doflamingo's crew, and is said to be one of the top three members of the Donquixote Pirates. He also has his own division, with Violet, Sugar and Jora being the most notable of his known subordinates.
He is a very powerful sniper, as he managed to create a bullet made of his sticky substance with his index finger and fire it at a very high speed with very precise aim, being able to hit a fly directly between the eyes while piercing a wall with explosive force, and blasting through three layers of reinforced concrete. He is extremely fast as he quickly leaps to the far away men that Robin is pointing to near the docked ship in the harbor, he covered a long distance in a matter of seconds, he then quickly leaped back to Robin once he realized he had been tricked. He also possesses tremendous strength, as he managed to lift a giant ship out of the harbor and throw it far away like a flail, while at the same time smashing the ship halfway through a concrete domed roof, nearly destroying the dome.
Trebol was able to defeat the entire Dressrosa army, alongside Diamante and Pica.