Otis grew up in the city of Alexandria during the 1st century BCE. As a child, his parents would bring him to the Temple of Amun in Siwa, causing him to fall in love with the village. He eventually became a royal scribe the royal court of Ptolemy XIII.
At some point after Cleopatra became the sole ruler of Egypt, Otis was contacted by Gamilat, the leader of the Nabatean rebels in Sinai with regards of a possible invasion of Egypt by Gaius Julius Rufio, a Roman general with served under Julius Caesar. As Siwa was a target in the attack, Otis later contacted Amunet, a founder of the Hidden Ones and through her, he was able to locate her husband Bayek's whereabouts. Otis sent a messenger to contact Bayek, informing him of the danger Siwa was facing. He also invited the Hidden One to meet him in his home in Alexandria after he dismantled the operations.
Eventually, Rufio discovered that his plans were discovered and thus sent his men to eliminate Otis in his home. Before being slain by the Roman soldiers, Otis was able to hide a papyrus meant for Bayek in a vase, who later discovered it after thwarting the invasion plot.