Roco originates in Eden as Eve's pet fox. Banished alongside Adam and Eve, he separates from other creatures and finds a mate, establishing a lineage whose descendants mirror his distinctive appearance and narrative roles across biblical history.

He stows away alone on Noah's ark. After the flood, he discovers a female fox adrift on debris, reuniting with her beneath the rainbow. At the Tower of Babel, he travels with Asaph's group but vanishes during the tower's collapse.

Rescued from a sandstorm, Roco is adopted by Abraham's wife. His disruption of livestock prompts Abraham to cast him out, an act that unintentionally diverts bandits from Abraham's caravan. He later reappears near Abraham's wife with a mate and cubs. Fleeing Sodom and Gomorrah's destruction, he escapes with other animals, clinging to a mule's rope.

Moses adopts Roco as a cub. He lives domestically until a wild fox lures him back to the wilderness. Roco witnesses Moses receive the Ten Commandments. During the Exodus, he accidentally startles hidden Egyptian soldiers into revealing themselves. At Jericho, he aids Israelite spies by attacking a city official and fleeing the collapsing walls through a fox-sized tunnel.

His appearances lessen later. He serves briefly as King David's companion. During the Babylonian exile, he is seen with the prophet Ezekiel, guiding travelers to an oasis and dodging soldiers. Near an unnamed prophet, a villager gives him fish before a soldier throws him aside.

Roco communicates primarily through animal sounds, occasionally speaking human language to other creatures. His narrative roles include providing comic relief through mishaps, acting as a neutral observer of biblical events, and sometimes altering outcomes by revealing threats or enabling escapes. His lineage persists, maintaining visual continuity while periodically resetting his relationship with humans.