Sierra

 Sierra is Kevyn's older sister. Sierra has been taking care of Kevyn for as long as she's known. Only she knows their past, but she never tells Kevyn and Kevyn never asks. Sierra is also a fan of Scubaman, much like Kevyn. Though she cares much for Kevyn, she never shows it. She even made fun of Kevyn's death by telling Kevyn not to die again.