Radioaktive was a normal Azul, once called simply Pet Name. Then one unfortunate (or fortunate?) weekend, they happened upon a radioactive potion. The young Azul, being only a few minutes old, drank the potion, and was transformed! They are henceforth and forevermore (because I can't afford those renaming tickets, yo) known as Radioaktive, for that potion they drank as a babe.

The End!