Cleo is extremely royal, so she expects everyone to treat her like it. Usually, her attitude is selfish, spoiled, and arrogant; she can't be entirely blamed for her behavior, because it's shown that she was raised to be like this. She is extremely competitive with other ghouls, especially Toralei Stripe. But deep down, Cleo's a very caring, kind, and thoughtful ghoul who cares about her friends.
Although Cleo has been known to take advantage of her friendship with Ghoulia Yelps by using her as a personal assistant or cheating off of her, she's very kind to her, and has helped her to overcome her shyness, showing that she really does care about Ghoulia Yelps and the friendship they share.
She can work well with the others if they share a common goal, like trying to avoid the gym teacher or helping Draculaura find her "perfect guy", in which case she becomes the de facto leader of the ghouls. She's a highly effective organizer, and leader.
In the first half of the Volume 1 webisodes, Cleo was the main antagonist and was archrivals with Clawdeen Wolf, but she eventually becomes much nicer to the ghouls. At the start of Volume 2, she's finally confronted with her own uncompromising, overbearing nature when all the fearleaders except Frankie Stein quit.
Cleo de Nile's a mummy in the possession of long black hair with brown (which varies in shade in the webisodes and on the doll) and gold highlights. Her skin is mocha colored, smooth and flawless. She has turquoise eyes, though they've also been depicted as green. Many parts about her points to her regal heritage, such as her ever-present burial wrappings, which she has to wear lest she disappear into dust, and a blue jewel under her right eye. Generally, she wears thick bright eyeshadow, highly pigmented lipstick (cherry red, gold, blue, green), and always wears thick black Egyptian-style winged eyeliner.
In Monster HighEdit
Cleo de Nile with her sister, Nefera de Nile, and her father, Ramses de Nile.
Cleo lives with her father, and older sister, Nefera De Nile. Her dad's name is Ramses De Nile, and he's an antiques dealer. So far, nothing is known about Cleo and Nefera's mother. In The Ghoul Next Door, Nefertiti is said to be the girls' aunt.
In the webisode "Miss Infearmation", Cleo mentions having an older sister called Nefera de Nile, who's out of the country with their father. Clawd's 'School's Out' diary also mentions Nefera being the previous fear squad captain. Nefera is said to be a model in Cleo's 'School's Out' diary. Based on both the 'School's Out' diaries and the cartoon, Cleo and Nefera don't get along very well.
At the beginning of the series, Clawdeen's angry with Cleo for dumping her brother Clawd, but now Cleo and Clawdeen are best friends and on the fear squad together. She's friends with Ghoulia Yelps, and they even plan their school schedules together. Ghoulia often serves as Cleo's personal assistant ("Copy Canine", "Mad Science Fair"), but also shows her great kindness as well. She's sometimes bossy and demanding to the other ghouls, but she's also shown to be afraid of opening herself up to deeper friendships and making herself seem vulnerable. As the series has progressed, she has mellowed out and become much nicer and GFFs with the other ghouls.
Cleo de Nile's pet is a snake named Hissette, whose attitude reflects Cleo's. In the Monster High book series, Deuce gave Hissette to Cleo as a gift, saying she was his mom's 'first gray hair', yet in her diary, it was stated that it was given to her as a gift from Egypt. In the books, Cleo also has seven cats named Chisisi, Bastet, Akins, Ebonee, Ufa, Usi, and Miu-Miu. This is a reference to how cats were worshipped by people and cherished and treasured, especially by royalty, in Ancient Egypt.
Cleo's dating Deuce Gorgon. She used to date Clawdeen Wolf's older brother Clawd Wolf, but according to Ghoulia it was a messy breakup. She said that it doesn't help that Cleo started dating Deuce the next day. The Relationship between Clawd and Cleo, however, was only the result of C.A. Cupid's arrows. Even if Deuce occasionally gets tired of her competitive personality, his feelings for her are true. It states in C.A. Cupid's diary that Cleo and Deuce started dating on November 1st.
Story of Joining Sora's TeamEdit
During Lock, Shock, and Barrel's mission in Monster High, they pranked each student of Monster High. They switched Cleo's make up with stinging chemicals that only sting for a few mins, but the only ones they haven't pranked was Jackson Jekyll and Twyla, because of how Manny Taur bulllied him and how he only gets invited to parties because he and Holt Hyde share the same body. And Twyla was a very shy ghoul and showed the trio kindness. So the trio began to persuade Jackson and Twyla to join the team and become friends. After Jackson and Twyla accepted, music was turned on from the school party and Jackson turned to Holt. Holt then ratted the trio out and the students began to surround them. But right when everyone was going punish the trio, Heartless, Nobodies and the Unversed were about to attack Draculaura and Ghoulia Yelps. But before they did, the trio moved the ghouls and took the fall, and the students saw the trio fighting the REAL enemies. Lock took down the Heartless, Shock took down the Nobodies, and Barrel took down the Unversed, and as the battle ended, Draculaura and Ghoulia Yelps were thankful to the trio for saving them. But when Lock, Shock, and Barrel fainted, the students nursed them back to health. As the trio woke up in the nurses office, they were confused of why Frankie and the ghouls nursed them back to help, and as the students explained, they were all forgiven and the trio explained about the Heartless, Nobodies, other worlds, Kingdom Hearts and Master Xehanort, the students were shocked about their world about to be consumed in darkness. Then after Sora, Kairi, and Riku came in the nurses office from the Gummi Ship to bring the trio back to the ship, the entire Monster High student body asked to join to help. Just when they asked, Lock, Shock, and Barrel asked also, and said that they'd be big help, and just as Sora, Kairi, and Riku disgused it, they all agreed and the students joined the team.