Clarisse is generally hot-tempered, arrogant, brave, and strong like most of her siblings. She is also known as a bully that dunks new campers' heads in toilets. In The Battle of the Labyrinth Clarisse shows strong feelings for Chris Rodriguez and shows her kind and caring side to him, even before he becomes her boyfriend. Clarisse is very proud and defensive of her cabin, and often defends the camp from monsters. She is also defensive and very protective of her good friend Silena Beauregard after she gave Clarisse some dating advice.

Although never seen in a one-on-one duel with anyone in the series, Clarisse is a fierce and daring warrior, and is all too aware of this, taking extreme pride to the point of hubris in her own combat skills. Her anger toward Percy increased after he defeated her father. During The Last Olympian, she is angered by the camp for never respecting the Ares' Cabin. Her pride even prevented her from allowing her cabin from fighting in the war until Silena's intervention.

She is similar in that way to Achilles, in the sense that her pride sometimes gets in the way of her good sense. This also makes her extremely similar to her own father, Ares, in that they both value strength as a primary advantage - although, Clarisse does not only rely on strength, and is an extremely charismatic leader who even Percy recognizes to have inspirational bravery. 

Clarisse is described as having the height of a basketball player and the muscular body of a rugby player, making her the most physically adept female fighter at Camp Half Blood. She has dark "pig eyes," and pale brown hair that is described as stringy. Percy also described Clarisse, along with the rest of her siblings, as having the same vicious sneer as their father, Ares. After returning from her scouting mission in The Titan's Curse, she has a new scar on her chin and her long hair is cut short and ragged "like someone had attacked it with a pair of safety scissors."