Cerberus and Spinal

CERBERUS (KERO-CHAN)
Cerberus is the guardian of the mystical yet dangerous book of Clow cards. He is the guardian of the sun, one of the two duty bound to protect the powerful cards, and opposite of the lunar guardian, Yue. For several decades he was locked away in the book of the Clow, which held the cards upon the death of their previous master, Clow Reed, until a new master appeared to take hold of the cards and their guardians. Cerberus’s character first appears at the beginning of the series when this new master, Sakura Kinomoto, releases him from the book. Once Cerberus is awakened (he was napping on the front cover) and released from the book he discovers the Clow cards have vanished, and appoints Sakura the title of Cardcaptor, and sends her off to retrieve the cards. Cerberus’s major role in the first half of the story is to select the candidate to take up his old master’s footsteps and inherit the Clow Cards, and to aid the candidate in their task of collecting the now awakened cards. Once all of the cards are captured and the Cardcaptor’s name is written upon them, Cerberus’s chosen candidate is then judged on their worthiness to own the cards by the other guardian, Yue. In the second story arc, Cerberus’s major role is to help and protect Sakura as she faces numerous challenges set upon her by another sorcerer, Eriol Hiiragizawa, in order to force Sakura to transform the Clow cards under her own power. In the final confrontation with Eriol at Tokyo tower, Cerberus helps Sakura to transform the Light and Dark cards by transferring his power into her staff.

SPINAL SUN
Spinel Sun (スピネル・サン, Supineru San^?) is the cat-like magical guardian created by Eriol Hiiragizawa as a counter part to Clow Reed's original guardian Cerberus. Spinel Sun's true form is a winged black panther, while his false form is similar to a small winged cat. Nicknamed Suppi by Ruby Moon, Spinel Sun spends most of his time reading and projects a calm demeanor. Ruby Moon often teases him that he needs to have more fun. During the series, he mostly remains out of sight of the main characters, except when he once runs into Cerberus in his false form. Fortunately for him, Cerberus doesn't suspect anything and instead declares him a monster and feeds him sweets, not realizing that the sweets would turn Spinel Sun into a hyperactive eating machine. Cerberus does not learn his true identity until just before the final battle where the two cats face one another. Initially, Spinel Sun appears to have the upper hand, however Cerberus' greater determination to protect Sakura enable him to defeat him.