Decky Millar (short for Declan) is Alex's, Ryan's and Derek's youngest brother. He is 8 to 10 years old and is currently living with his Dad and his two older brothers in Scotland. His mum died.
One night before Alex's death, Decky and Alex went to an amusement park. Alex had to leave earlier since she had an appointment with Hal, so she promised Decky to return tomorrow to the amusement park. But she died during the meeting with Hal and could not keep this promise.
Since Alex has died his older brother Ryan takes car of him and his other brother.