Keroberos

Keroberos is one of the main characters from the Cardcaptor Sakura anime and manga.

Keroberos is one of the two Guardians of the Clow Cards created by Clow Reed, along with Yue. Before his death, Clow appointed Kero as the one to select the potential candidate to be the next master of the cards, Cerberus himself, and his fellow guardian, Yue. After Sakura Kinomoto inadvertently releases the cards, Cerberus chooses her to be the candidate and teaches her the basics of capturing the cards.

Appearance
In his borrowed form, Keroberos resembles a lion cub or rather a stuffed animal or a plush toy with yellow-orange fur, big ears, and small, white wings.

However, his true form is that of a huge, tawny mane-less lion or cougar, with enormous, angelic, white wings and a breastplate and helmet of metal, studded with a large, red, precious stone.

Personality
By nature, Keroberos is bossy, demanding, and gluttonous, but he also genuinely cares about Sakura and believes that she will become the next Master of the Clow as he acts as her guide to gather the Cards.

He is responsible for giving Sakura the Sealing Wand, having appointed her to be the one to recapture the Cards she unknowingly released.

Kero's hobbies include playing video games and eating snacks and sweets (he loves sweets more than almost anything), even though, drawing his power from the sun, he generates his own energy, and does not need to eat to survive but unlike Yue, he enjoys the finer things in life.

He has a particular fondness for cake, cookies, and chocolates. In the anime, he was also intoxicated by a box of brandy chocolates, causing him to become drunk.

Despite his fondness for sweets and other food items, he is not often above sharing, provided there is enough left for him (except in episode 10, season 3 when he intoxicated Spinel by unknowingly forcing a doughnut into Spinel's mouth, resulting in the creature gaining a sugar high before proceeding to run all over Tomoeda Elementary, causing havoc).

Keroberos also enjoys being filmed by Sakura's best friend, Tomoyo Daidouji and, unlike his Mistress, relishes the costume accessories he is asked to wear for these recordings.

Even though he has been a willing servant all his life, Keroberos can be somewhat of an egomaniac, obsessing over his "coolness", and is seen bragging about himself after watching most of Tomoyo's recordings.

Despite his sometimes erratic behavior, Cerberus is remarkably intelligent. He is knowledgeable not only on the Clow Cards, but also on all forms of mysticism, with a knack for reading magical auras. At one point, this leads him astray when Kaho Mizuki tricks him by using her strong, moon-aspect aura to cover up Yue's, preventing Cerberus from realizing Yue's false form. In addition to this, Cerberus is also not quite as carefree and without inhibitions as he seems at first glance.

CLAMP describes Cerberus's "favorite thing" as "loud fun", and his least favorite as "being sad or lonely". Cerberus doesn't like wallowing in life's sad and depressing facts, which could possibly be why he takes up so many indulgent pastimes, like food and video games, to distract himself from them.

This does not, however, mean that he is immune to these realities, as is shown in the first arc of the series when he is seen frequently musing about his fears concerning the rapidly approaching Final Judgment to the point of obsession. His lack of communication regarding the Final Judgment nearly causes Sakura to fail, as she is unaware that Yue can turn the power of any Clow card under his jurisdiction back at her, but thanks to Kaho, Sakura is eventually able to defeat Yue, becoming the new Master of the Clow Cards while also gaining a new Staff in the process as with Kaho's Bell of the Moon, her Sealing Staff changes from its original structure to resemble that of a single star.

Voice and Mannerisms
Because the Clow Cards had been in Osaka for a long time, Keroberos speaks in the Osaka dialect, which is famous for its plain speech and unique slang. In the English dub of the series, his plush voice is rather high and he speaks with a New York accent, but transformed, he speaks with a more adult, low pitch.

Abilities
His powers are based on the Sun and his power comes from Western magic.

Sensing: Keroberos has the ability to sense the Clow Cards and magical presences. While he can usually determine their exact attributes through this Sensing ability, it has been proven that interference from powers far superior to his can hinder his Sensing, as seen when Eriol Hiiragizawa (1/2 of the reincarnation of Clow Reed) could effectively conceal his exact whereabouts and identity from both Keroberos and Yue until he personally revealed who he really was.

Basic Plushy Powers: While in his plushy form, Keroberos is still able to fly, but cannot use any of his magical abilities aside from his (weakened) abilities of Sensing, spreading tiny fireballs (as seen at the end of episode 35) and breathing fire (as seen in episode 45 when fighting the Earthy).

Clow Cards: In his true form, he has jurisdiction over all things fire and earth, the elements which draw their power from him.

Energy Barriers: Keroberos is able to summon protective energy barriers to protect himself and others from both physical and magical attacks.

Fire Breath: As fire is one of the elements under his control, Keroberos is able to shoot balls of fire from his mouth.

Cards
Half of the deck are under his protection, and these are the only cards that can effectively be used against Yue. The Elements he controls are The Firey (his aggressive element) and The Earthy (the slightly more passive Element under his jurisdiction).

Trivia

 * Apparently, Kero spent 30 years asleep in the Clow Card Book before Sakura released him.
 * In the anime, Sakura eventually made him a small "home" in her bottom desk drawer.
 * The drawer where Kero "lives" is just below the drawer where Sakura keeps the Clow Book; in the manga, he sleeps in Sakura's bed.
 * Like Tomoyo Daidouji which usually has a habit of ending phrases with, "~wa", he usually has a habit of ending phrases with "~ya" too. (Ex.: "~ya-de", "~ya-na", etc.)
 * Both of Kero's false and true forms are the appearance of a lion; his powers being related to the sun is based on the alchemy symbol of a lion devouring the sun.