-Octoroo handing Malladus Uno a bowl of Sanzu Water.
He first appeared in Operation: ANCESTOR's prologue, giving Malladus a bowl of Sanzu Water. Throughout most of ANCESTOR's plot, he and Dayu were aboard the Demon Train, discussing how Eva (Numbuh 10) bared a strong resemblance to the long-lost Ocean Princess. When Octoroo told this to Malladus, the Demon King demanded that he not tell Davy Jones. Octoroo secretly refused as he sent a Kargarok bird with a letter to Davy Jones. During the final battle, Eva and Kade fought Octoroo and he escaped through a gap, then dragging Dayu with him after Malladus was defeated.
Both he and Dayu made a return in Operation: DUTCHMAN, working with Davy Jones and his crew. In that story, Octoroo told Sector Z how both he and Jones fell in love and were betrayed, and that Davy Jones saved Octoroo when he was drowning at sea, the two became close friends after hearing the others' tales. In the final showdown of that story, Octoroo and Dayu fell into the maelstrom when Nigel attacked them.
Octoroo survived that encounter as he returned in Legend of the Eight Firstborn, having become a member of the Brotherhood of Evil. He was defeated by Eva once again and frozen with the other villains.
Octoroo seems to hang around Dayu more than any other Nighlok. Dayu seems to be in on all of Octoroo's private plans.
Octoroo is one of the Demon King's most loyal servants. However, Octoroo claims that his loyalty is to Davy Jones first.