Changelings

They are Ronan Born for Water Shongili and Murel Monster Slayer Shongili. Twin brother and sister. Children of Yana and Sean. Children of Petaybee. As such, theirs is a destiny deeply intertwined with the sentient planet that is their home. For Ronan and Murel are more than human. Like their father, each can transform into a seal and converse telepathically with the planet's creatures - such as the friendly otter whose life they save one day from a pack of ravenous wolves.
But the twins' bravery has unforeseen results when a visiting scientist witnesses their startling metamorphosis and becomes obsessed with their capture. To protect their children, Sean and Yana send them to stay with a powerful family friend on an orbiting space station. But no one realizes that Ronan and Murel hunger to discover the origins of their shape-shifting talent - and that their search for knowledge will place them squarely in the path of peril.
Meanwhile, Petaybee is changing - and much faster than an ordinary planet's natural evolution. It appears that portions of the sea are heating up and a landmass is suddenly rising from the depths. To investigate the startling occurrence, Sean heads out to the open water in his seal form. But the newly unstable region holds untold mysteries - and the potential for disaster.