The Storm picked up Duffie from under the noses of the Warriors, discovering him playing rugby in Auckland.
"When you support a team, you want to play for them, but it was never really an option," said Duffie of Melbourne's recruitment. "I never really got to the point where it was Warriors or Storm, it was Storm or nothing."
With an NRL grand final berth up for grabs, Duffie has the unenviable task of marking his former hero, powerhouse Manu Vatuvei.
"The boys will help me out a lot. I don't think he's really a one-man job," he said.
Melbourne's 18-14 loss to the Warriors this season in round seven is also a match that sticks in Duffie's mind as he described it as the worst of his NRL career.
The Storm back three were peppered with high balls, with Duffie among those to commit crucial errors which led to Warriors' tries.
"It was my worst game under the high ball and I've never forgotten that game and I want to make up for that," Duffie said.
"I wasn't very happy after the game and I wanted to make it right and, since then, I've been good under the high ball.
"Every day I've been practising and that's not going to change this week so, hopefully, I can keep that going."
- AAP