Aiden Gillespie was born in Aviemore, Scotland to Lorne and Mhairi Gillespie. He was raised by a single father after his mother left, and grew as an unathletic and socially insecure youth, playing the "round-bellied ginger boy who likes to listen", used as a confidant by girls who treated him like an "harmless little pup". His father was so busted up after Aiden's mother left, that he didn't manage to tell his son about girls. His father's thoughts on the topic were mostly angry and confusing.

In his early teens, while playing in the Glenmore Forest Park, Aiden gained the body of an immortal Celtic warlord when his soul was merged with his spirit. Since then, Aiden started changing, initially a couple times a month, and struggled to suppress the fighting craving of his muscular warrior form.