Riprap and Ebbie are Sandy's biological pups and Gray's younger siblings. They were introduced in the Battle of Riptide.
Battle of Riptide[]
The twins are first introduced in this book and are nurse sharks, like Sandy. When Gray meets them for the first time, they don't speak yet. It is unknown whether they can't or won't speak yet. Gray says they're so cute, much cuter than he was when he was a pup and explains to his mother about being a megalodon.
Into the Abyss[]
Riprab and Ebbie are now able to speak and are led away to safety by Sandy and the remaining members of Coral Shiver from the growing threat of Emperor Finnivus.